2020 Gmc Sierra 1500 Engine Problems

Your transmission's internal pump gears failed catastrophically at under 70,000 miles, sending metal debris throughout the transmission and damaging the exhaust converter. The vehicle made an extremely loud noise before breaking down on the highway with passengers aboard, creating a safety risk. Your GMC dealership has confirmed this damage. Fixing this will require transmission replacement and exhaust converter replacement.

Your engine is making knocking sounds and vibrating noticeably at 28,000 miles. An auto shop has indicated the engine may be severely damaged. This typically requires engine diagnostics and potentially major engine repair or replacement.

Your engine has experienced complete failure at 84,000 miles. This is a serious issue that requires a full engine inspection or replacement to diagnose the root cause and restore your vehicle to working condition.

While driving on the highway with your children, your check engine light suddenly came on without warning, and your engine immediately lost power, made knocking noises, and misfired. You safely pulled off the highway and had the car towed to the dealership, where technicians found internal engine damage to the valve lifters, rods, and camshaft. The owner believes this represents a serious safety issue and notes similar complaints exist online regarding the 5.3L engine.

Your engine suddenly stopped working while you were driving with no warning lights or signs beforehand. A mechanic found that an internal engine lifter failed and damaged the camshaft, which appears to be a manufacturing defect rather than maintenance-related. This unexpected engine failure forced you to stop in traffic and created a serious safety risk for you and other drivers. Fixing this issue will likely require engine repair or replacement of the failed lifter and camshaft components.

Your check engine light came on while driving at 40 MPH. The dealer diagnosed a faulty oil pump solenoid and replaced it, but after the repair, your engine seized and stopped working. This happened at approximately 45,000 miles. The repair may involve replacing the oil pump solenoid and diagnosing why the engine seized after the initial repair.

Your engine is making a distinct knocking sound, especially when you accelerate from a stop. The knock is loud and noticeable during hard acceleration. The repair will likely involve internal engine work to inspect or replace the rod bearings.

Your engine made an unusual noise while idling without any warning lights appearing on your dashboard. When the dealer inspected it, they found that the crankshaft and thrust bearings had failed inside the engine. The dealer disassembled and repaired your engine, and the manufacturer covered part of the repair cost. This happened at 60,000 miles.

Your 2020 GMC Sierra Denali's 6.2L engine developed a stuck lifter on one bank and a bent push rod, causing a popping noise when starting. The dealership quoted $9,200 for repairs or $9,600 for a complete engine replacement with warranty. This type of failure is unexpected on a low-mileage, well-maintained truck. Fixing this will likely require either removing and repairing the cylinder head to replace the lifter and push rod, or replacing the entire engine.

Your engine hesitated when starting and displayed warning lights for the check engine and diesel exhaust fluid (DEF) system. Your vehicle showed a message saying you had 94 miles before it would enter limp mode and was limited to 65 mph. A dealer diagnosed that your DEF tank pump assembly had failed and needed replacement.

Your truck developed a prominent metallic ticking sound at 96,000 miles, which was caused by a collapsed hydraulic lifter in cylinder #1. The dealer confirmed the lifter failure also caused significant wear to the camshaft, requiring both parts to be replaced. The service manager noted this is a common issue with 2020 6.2L engines and attributed it to a design flaw involving Dynamic Fuel Management and GM's oil viscosity recommendation. The repair will involve replacing the hydraulic lifter and camshaft.

Your engine started making a knocking sound and lost power, requiring about $3,500 in repairs. The problem was caused by failed valve lifters and a damaged camshaft, which created the knock and power loss. The repair will likely involve replacing the lifters, camshaft, and related internal engine components.

Misfiring due to DFM which is a common issue. Running a scan confirmed. I have installed a AFM/DFM disabler which seems to fix the issue.

Have not had my truck in over a month while it’s getting repaired had engine failure sure to faulty hydraulic lifters and camshaft failure due to the Dynamic fuel management system purchased warranty for my vehicle but this needs to be looked into it is unfair as a consumer that they are not doing anything about 2020 models and earlier they are just focusing on 2021 and up. They almost had me crash my truck due to power loss

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, there was a loud rattling sound coming from the engine. There was no warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed with crankshaft failure. The contact was informed that the crankshaft could be replaced; however, the dealer suggested that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 44,000.

I had a complete engine failure that I had to pay out-of-pocket for I really think that this vehicle should’ve been included in the 2021 and beyond engine recall for 6.2 GMC Sierra‘s. I drove to work one morning Fein after work I turned my vehicle on, and the engine started shaking violently and smoke coming out of my exhaust like I’ve never seen it before dealer said engine was completely blown and had to be repaired again I paid for this out of my own pocket. It is now coming to my attention that this vehicle is being looked at as an engineering analysis in line with the recall for the 2021 in above GMC Sierra‘s what do I need to do?

Engine failure as related to RQ26-001. engine misfires after following recommended maintenance schedule for 6.2L engine. Vehicle is at dealership and available for inspection and dealer is recommending engine replacement. Engine light came on and was brought to GMC dealership same day.

Catastrophic engine failure at 62,445 miles. Dealer state excessive oil in cylinder 7, ring failure. Recommendations; remove and replace engine.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the engine made an abnormal popping and crackling sound. The traction control, check engine, and several other unknown warning lights were illuminated. The message "Service Emergency Brake" was displayed. The engine later made knocking sounds, and the vehicle vibrated while driving. The vehicle was towed to an independent mechanic, who determined that the engine needed to be replaced. The vehicle was not repaired. The contact related the failure to NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); however, the year and VIN were not included in the recall. The manufacturer was made aware of the failure and advised the contact to file a complaint with the NHTSA Hotline. The failure mileage was approximately 138,000.

I purchased my 2020 gmc sierra 1500 6.2L in September 2024 with 80,000 miles. 9 months later the lifters gave out. Had them replaced and 6 months later, the lifters again were bad and was knocking. They are now replacing the lifters and cam. I am so disappointed that this is happening. I hear that the 2019 and 2020 was not included in this recall! Why not!! If it’s still doing the same thing and it is the same engine, why isn’t my truck in this recall? I would like to know why? If it is doing the same thing as the recall, shouldn’t it be covered by this recall? Best, [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed and hauling a boat, the vehicle shook violently and made a loud banging sound. The vehicle failed to accelerate above 40 MPH. The check engine warning light was illuminated. The vehicle was towed to the dealer, and it was determined that there was a misfire in cylinder #6, and that the engine required further inspection. The vehicle was not repaired. The contact related the failure to NHTSA Action Number: EA25007 (Engine, Engine and Engine Cooling). The manufacturer was not made aware of the failure. The failure mileage was approximately 87,000.

The bearings in my engine failed while on the road! The dealer says I need a full engine replacement for $16,000. There were no warnings or indication there was a problem. The vehicle has been maintained perfectly since it’s purchase.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the engine seized. No warning lights were illuminated. The contact disabled the stop-to-start feature, and the failure ceased. The vehicle was taken to the dealer, and the contact was informed that the repair was not covered under recall. In addition, the contact was informed that the vehicle needed to remain with the dealer for two weeks while performing diagnostic tests on the vehicle. The contact was unable to be without a vehicle for two weeks. The vehicle was the only means of transportation. The contact stated that the failure was a known failure with the vehicle and that the manufacturer needed to repair the vehicle. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was made aware of the failure, and a case was filed. The contact was informed that the repair was not covered under the recall. The contact was advised to take the vehicle to the dealer for a diagnostic test. The failure mileage was approximately 123,000.

Truck started to vibrate and loud tick sound, CEL for misfire and traction control. Hard shifting until I could pull to a safe area to call for a tow. Around 76k miles on the truck when it happened.

While accelerating on the highway the truck started to vibrate along with a loud tick, CEL came on for misfire and traction control, hard shifting to where I could park at a safe area to wait for a tow. Kids in the car with me 90 plus degree day on the side of the highway.

When driving at about 30 mph the truck randomly shut off and would not start or try to start. I was later told the engine crankshaft rod bearings seized.

Sudden engine issue. Knocking, power loss, brake and steering warnings. Severely damaged engine. Mechanic says 2 cylinders are irreparably damaged and entire engine must be replaced

Driving to the lake on the highway towing a trailer, a loud tapping noise started followed by vibration. Engine seems to have lost power during acceleration.

MY 2020 GMC SIERRA DENALI EXPERIENCED A COMPLETE ENGINE FAILURE in June of 2024. Dealer repair was in excess of $7,700.00. They stated they knew this was going to happen at about the 70,000 mile mark as they have fixed many in that same time. Repair resulted in rod replacement and cam shaft damage and replacement.

We were driving down the interstate at about 75 mph when a message came up that said to shift to neutral and push the start button. My husband did and it continued to drive perfectly fine, but about 6 miles down the road it did the same thing again except when he pushed the start button it did not start. I cannot begin to tell you the cause as to why it would’ve been doing that as I have never had any other issues with it.

Bought the truck less than four months ago and as of yesterday it consumed a substantial quantity of oil and later refill. However today it made a noticeable noise until it shut off permanently. Dealer did not disclose this

I started to notice changes in performance around 75k miles. Seemed like performance was subpar compared to what was the norm. Seemed to lose some power. Minimal at first, more so just recently around 90k. Oil consumption was starting to accelerate at each oil change at 75k, 80k, 85k, 90k. To the point around 85k and 90k that I would not go over even 1 mile from the 5k threshold without changing the oil. Around 90k I could tell it was not getting any better, deficiencies were accelerating it seemed. At 91k miles I started to hear clicking noises and loss of power, starts were getting rough, bouncing at idle. I stopped driving it, only driving it to the dealership where I brought for a look at it. Will be driving it again for them to do a deeper diagnostic. Many misfires at cylinder 5. PO305 the issue. Showed up around 91k miles on 12/17/25 Now investigation into my model. I see online.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving approximately 35 MPH, the vehicle lost automotive power with the check engine warning light illuminated and the message "Vehicle Might Lose Power" displayed. The vehicle remained at the residence, and the contact used a self-diagnostic tool to retrieve a fault code related to the coolant valve D. The contact determined that the coolant valve D needed to be replaced. The vehicle was taken to an independent mechanic; however, the contact was unaware of the part that needed to be fixed in the vehicle. The vehicle was repaired. The contact researched and was made aware of an unknown NHTSA Campaign Number; however, the VIN was not under recall. The manufacturer was contacted and confirmed that the VIN was not under recall. The failure mileage was approximately 31,000.

Fuel management system caused a lifter to fail (stuck) which resulted in camshaft damage at 77,611 miles. GM refused to cover the repair, although there is a pending class action lawsuit against GM for this very issue. Truck was repaired at a GM dealership - Sunrise Collierville, TN. Repair costs was approximately $7,000. This occurred during a 2.5 hour road trip which put lives at risk. The truck began to vibrate, and the check engine light came on. There was no other warning before the failure occurred. No police or insurance were involved. This occurred on 9/27/25. It took the dealership 32 days to diagnose and repair the issue. Thanks.

In December of 2023 my 2020 GMC Sierra 1500 was driving down the freeway, experienced a jerking and low oil pressure. Pulled over and shut vehicle off and wouldn't turn back on, engine locked up. The vehicle received a brand new 6.2l replacement motor in April of 2024- $15k in parts and labor. This vehicle was not included in the recent recall, but obviously experienced a similar issue. This was at 75k miles. The car was owned by a different owner at the time of the engine failure. I bought the vehicle as a repo and proceeded to get the engine fixed on it.

Engine lost all power while driving highway speed. Vehicle towed to Cavender Chevrolet dealer in Boerne, TX. Dealer inspected and determined cam bearings damaged. Engine replaced with remanufactured engine.

Driving on the Highway, the engine shuttered, but kept going. When I had to slow down, the engine stalled and would not restart. It left me in the center lane of a three lane highway. I was able to push the vehicle off to the side of the road. Very dangerous. No warning lights came on, no alerts. I had the truck towed to Folsom Buick & GMC in Folsom CA where the diagnosed a complete engine failure. The have now had my truck for a full month. They are trying to get GMC to share the cost of the replacement motor. In the meantime, I'm renting a pickup truck so I can continue to work.

Engine fan has been constantly running, with engine temp reading around 230 consistently. After driving 5 miles on the interstate it shot up to 260 and said “engine temp overheating, idle engine”.

I am Having direct issues with the engine when the vehicle is started and continues while idling or driving at any rate of speed.There's a continuous "Knocking" noise that has concerned me for a while now. My vehicle (2020 GMC Sierra 6.2 liter gas engine) with almost 100,000 miles has been doing this for a while now (at approximately 50,000 miles) and (was documented at the dealership when I made a complaint which included what I considered the vehicle to be using/losing more "oil consumption" than the normal 3-4 quarts between oil change) dating back to 2022 0r 2023 when I was told by the dealership that the amount of oil being used/ lost still fit within the manufacturers specifications.

My 2020 GMC Sierra 1500 Denali with the 6.2L L87 V8 just began experiencing a new rough idle with intermittent RPM dips. There are no engine codes or warning lights. Idle drops are noticeable, suddenly began this week. I am concerned due to ongoing NHTSA Engineering Analysis EA25-007 involving this engine. Some owners reported engine failure with little warning. The truck has right over 68,000 miles on it and has had every oil changed performed at a GM dealer. I have had to top off the oil between cycles and always used the recommended oil, being the Dexos Gen 3 due to the truck burning a small amount of oil. More detail on a possible cause. I believe it would be worth investigating the DFM technology. I will be performing a fuel cleaner and possibly a lifter cleaner and/or additive. I would like to tune the truck and turn off the DFM since this is what I have read causes the truck to burn oil and damage the lifters. However, I will wait until this Analysis is completed before deciding to change the truck's stock tunes.

The engine failed and started burning oil at a rate of 3 quarts every two weeks. The vehicle is currently at the GMC dealership having the engine rebuilt at a cost of over 15,000. The vehicle has approx. 116,000 miles at time of failure, so it is outside of the manufacturers warranty. The GMC dealership (Fred Anderson Greer) has photos. The engine is a 6.2L but not currently under recall as it is a 2020, the recall includes 2021 - 2024 models.

This is the 3rd catastrophic engine failure since purchasing this new vehicle from the dealership, the vehicle is currently at the dealership and is available for inspection. The latest diagnostic report has been attached from the dealership for reference. My safety and the safety of others was at risk with each occurrence. The 1st occurred on the interstate when a lifter rod bent causing loss of power with no warning, engine was rebuilt by the dealership. The 2nd occurred on the interstate when a different lifter rod bent causing loss of power with no warning, engine was rebuilt again by the dealership. The 3rd occurred just recently while on a highway. The engine suddenly turned off with no warning. The dash told me to put it into neutral and start again. I had to coast the truck for a long distance after the sudden loss of power in order to attempt to restart the engine. The engine would not start. The diagnostic report from the dealership states "engine is seized tight, maxi fuse is blown, needs engine replacement."

My engine is currently being torn down at the dealership.I heard a ticking noise coming from my engine so I took to the dealership I bought it from and when they did their diagnostics and inspection they said it was a connecting rod bearing failure.

This is a report on an incident that happened a year ago. Vehicle was taken to GMC dealer who replaced the engine at our expense. Seems to be consistent with the problem on newer GMC's that have been covered by a recall. This 2020 is one of three GMC's owned by our company. This expense was in the $12,000 range. (The 2019 experienced similar issues in 2022 and the expense was $2800 ish, and in 2024 another $1200 ish. ) Dash lit up like a Christmas tree, all warning lights on. Stalled, barely moved.

Engine ticking especially when cold, dealership claims they fixed it while it was under warranty but it has continued to do it.

At approximately 54,000 miles had a complete engine failure. Lifter blew apart and damaged crank shaft. Complete engine rebuild. Rebuilt in approximately 3 weeks. 2022 At approximately 138,000 miles had another complete engine failure. Lifter blew apart again, Entire engine was replaced. New engine took 10 weeks to get. Installed in 2 days after recieved. 2025 No symptoms or warning lights present prior to failure.

Engine knock, loss of power, engine failure warning, ticking

While driving at highway speed and attempting to pass another vehicle, I experienced an engine failure; loss of power, noise from engine, and numerous warning messages on the display. At the GM dealer, I was informed that a pushrod (cylinder #2) was bent, the source of the engine noise. Upon further inspection (removal of cylinder heads), it was determined that the cam shaft chrome had begun to flake causing pitting (lobe damage) which in turn caused the pushrod to fail. Had the pushrod broke instead of bent at highway speed, I feel there would have been a catastrophic failure with more severe consequences for my vehicle and others around me. Vehicle was diagnosed and repaired by a certified GM dealer. There were no prior warnings/indications of problem(s). I understand there is a current recall of the GM 6.2L L87 engine for model years 2021-2024. This incident occurred on a model year 2020 GM 6.2L L87, but the issues I experienced are identical to the 2021-2024 engines identified in the recall.

I experienced lifter and camshaft failure on my 2020 GMC Sierra equipped with the 6.2L V8 engine at approximately 72,000 km. GMC denied warranty coverage as my factory warranty had expired only four months earlier. The repair cost me nearly $10,000 out of pocket. My vehicle has been meticulously maintained with regular oil changes performed at my local GMC dealer every 5,000 km, and it has always been fueled with premium gasoline as recommended by the manufacturer. The engine failure was sudden and unexpected. All lifters and the camshaft were replaced during the repair. Since the repair, I have noticed intermittent RPM fluctuation under light load conditions. I am currently working with my dealer to diagnose whether this issue is related to the recent engine repair or a transmission flush that was performed at the same time. I am extremely disappointed in GMC’s handling of this situation. Despite this being a well-documented issue with the 6.2L engine, I received no goodwill assistance or warranty consideration from GMC. While my dealer provided a partial discount on parts and labor, I was still responsible for nearly the entire repair cost. I hope GMC and NHTSA will review this matter closely, as owners should not be facing such expensive failures on well-maintained vehicles with this engine.

A lifter in my cylinder is bad and damage to my cam shaft. This truck also has the 6.2L engine that was recalled for other GMC Vehicles.My safety was put at risk as I was driving it and it started smoking. I have had 2 different mechanics look at it. One mechanic was an independent business, the other was a certified GMC dealer. There was no warning lamps or messages.

Rod bearings spun and engine locked up while driving 70mph on the freeway. I was in traffic, and had to work my way over and off to the shoulder of the road. The engine was diagnosed and replaced by Hiley GMC at a cost of nearly $5,000 out of my pocket. This was at approximately 63,000 miles. Just out of warranty. No loaner vehicle provided. I was without my truck for 2 months. There were no warnings at all. No lights or noises of any kind. Rod bearings spun again on the replacement engine approximately 35,000 mile later. It happened same as before. Driving on the freeway at 70mph, and the engine seized. No power steering, no warning noises or lights. I had to coast across lanes through traffic and onto the shoulder. Diagnosed and replaced by Jerry's GMC. They replaced the motor at no charge except I had to provide the new radiator because it was on backorder. They had the truck for over 3 months and I had no loaner vehicle. With approximately 65,000 miles on the latest engine, a lifter went out. I put it in the shop to have all the lifters replaced, and motor mounts replaced at a cost of $6500. Upon taking the truck for a test drive, the engine seized in traffic under an overpass and blocked one lane of traffic. The shop dropped the oil pan to check it out, and, lo and behold, this engine has spun rod bearings again. There is definitely a serious and dangerous problem with the L87 6.2L. Being a 2020, it is not currently included in the recall, but it needs to be included. I spun bearings the first time in August of 2021. I was hoping it was just bad luck. I hadn't heard of all the instances at the time. I've never had a major engine failure prior to this model, and this one has failed 3 times in the same truck with meticulous maintenance.

The check engine light went off and started blinking. The engine started making ticking noise. I pulled over. The check engine light kept blinking. I had the truck towed to the Chevy Dealership. They found damage to the lifter and camshaft. They had the truck for over 2 weeks. Luckily I purchased the extended warranty. But the repair still cost me 1,200.00 dollars out of pocket. And cost the warranty company over 9,000.00 dollars

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving 55 MPH, the vehicle failed to accelerate as intended while depressing the accelerator pedal. In addition, there was an abnormal sound coming from the engine. Multiple warning lights were illuminated. The contact was able to coast to the side of the road. The vehicle was towed to the dealer, where it was diagnosed with engine failure. The engine was repaired. Most recently, while driving 35 MPH, the vehicle failed to accelerate as intended while depressing the accelerator pedal, with an abnormal sound coming from the engine. Multiple warning lights were illuminated. The vehicle was towed to the dealer, where it was diagnosed with engine failure. The contact was informed that the camshaft, bearings, and lifters in cylinder #4 had failed. The vehicle remained at the dealer unrepaired. The manufacturer was notified of the failure. However, no assistance was provided. The failure mileage was approximately 19,000.

Tick sound coming from underneath. Also fumes smell. Dealership found it to be the exhaust system. Said the muffler valve is bad. Quoted me $2000 for repair. Never heard of a exhaust system failure in only 5 years. Very unsatisfied with this.

I noticed a ticking sound in my 2020 GMC Sierra 1500 SLT 5.3 Liter on 10/15/2025 after it was serviced at an Authorize Buick GMC Dealership on 10/13/2025. I made an appointment and returned the vehicle to the dealership for further inspection on 10/17/2025. I was informed later that day that my truck has lifters and camshaft failure. If my truck had stalled or stopped on the express way, myself and others safety could have been at risk. My truck has only been looked at by the dealership at this time, and it is available for inspection upon request. There were no warning lights, check engine lights, messages or symptoms prior to the failure. I did get a low oil level message in April 2024 when the dealership stated they must not have put the correct amount of oil in my truck during an oil change on 1/29/2024. They inspected my truck and assured me there was no damage done to my Engine from this issue. I have recently learned there is a recall for GM Vehicles manufactured between 2021 and 2024 with the 6.2L engine installed. I am not sure why this recall does not include 2020 trucks with the 5.3L engines installed. Apparently, the same problems exist with these engines also. I received an estimate for repair approximately $13,000 which can increase once the engine is town down and inspected further. Any assistance you can provide would be greatly appreciated.

The engine failed completely while driving. On the day of the incident, I started my 2020 GMC Sierra 1500 AT4, and immediately upon cranking, the engine began knocking loudly. I shut the vehicle off right away to prevent further damage and called a wrecker service to have it towed to Marianna Chevrolet, GMC. No warning lights or messages prior to the incident. The weather was clear and dry, and the truck was parked on level ground at the time. There were no prior warning lights, leaks, or unusual noises before this event. The vehicle has been well-maintained, with oil changes performed regularly every 4,000 miles at a local auto shop (though receipts are not available). The brakes were replaced earlier in 2025. Marianna Chevrolet, GMC inspected the vehicle and estimated the repair cost at $12,700 due to what appears to be a major internal engine failure.

43000 miles 2020 gmc sierra with lifter engine issues. Oil change made every 3k miles

6.2L V8 engine in 2020 GMC Sierra 1500 AT4 suffered two lifter failures, which damaged crankshaft and sent metal shards throughout engine and oil. Total engine replacement required. This issue is subject to a recall for 2021 - 2024 model years and the recall should extend to 2020 model years. Vehicle was traded without functioning engine at a significant loss in value for new vehicle, and is not available for inspection. Vehicle was inspected by service department at GMC dealership and traded to a different GMC dealer. No prior indications of problems or warning lights until engine failure occurred while driving.

Engine misfiring and rough idle with occasional flashing engine light. Dealer said no codes to know what to look for despite replicating issue. Eventually it threw a Cylinder 5 misfire and thus GM dealer was able to look further. They found metal in oil pan and concluded a bearing issue and would need to replace engine.

Engine timing chains failed at 71,000 miles requiring a $9,700 repair. Warranty covers 5 yr/ 100k miles and was not fully covered by GM since the vehicle was 9 months beyond 5 years, yet still well within the 100k miles. Issue was diagnosed via P0016-00 being set indicating misalignment between crankshaft position sensor and the intake camshaft position sensor. This issue is a known problem with the early LM2 engines, and the timing chain was upgraded in later LM2 engines. Early adopters of the LM2 are left to pay the price for a defective part.

The engine coolant control valve on my 2020 GMC Sierra 1500 with the LM2 Duramax diesel failed. The failed part is still in my truck, which remains at the dealership awaiting replacement. The repair is delayed due to the part being on nationwide backorder, further highlighting that this is a widespread issue. When the valve failed, the truck entered reduced engine power mode while I was traveling on the interstate. This limited my speed to about 40 mph while climbing a hill. The sudden loss of power in high-speed traffic created a serious safety hazard, as it significantly increased my risk of being rear-ended or involved in a collision with faster-moving vehicles. I drove the truck directly to the dealership after the incident, where the problem was immediately confirmed. The issue was diagnosed and confirmed by the dealership, which identified the coolant control valve as the failed component. To my knowledge, GM has not yet inspected this specific failure. Prior to the loss of power, the truck displayed a “Reduced Engine Power” warning message and the check engine light on the dashboard. These warnings appeared at the time of the failure. Importantly, GM has already acknowledged this issue by issuing Special Coverage N252508341 for 2021 and 2022 GMC Sierra 1500 trucks with the same LM2 engine and the same coolant control valve part numbers. However, the 2020 models (like mine) were excluded from that program despite using the identical part and engine configuration.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving approximately 40 MPH, there was an abnormal knocking sound coming from the engine compartment. The contact stated that several unknown warning lights were illuminated, and several messages were displayed. The vehicle was driven to the side of the road to safety and turned off. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The failure milage was approximately 76,000.

Vehicle: 2020 GMC Sierra Denali 1500 (VIN: [XXX] ) Description of the Problem: My 2020 GMC Sierra Denali has developed serious engine problems that create unsafe driving conditions. On [XXX], I documented loud knocking and clicking noises coming from the engine. The vehicle also shows warning lights and unpredictable performance. Because of these defects: •I cannot safely drive the truck without risk of engine failure while on the road. •The noises and mechanical issues raise concerns about potential loss of power, stalling, or catastrophic engine damage at highway speeds. •No independent mechanic will touch the vehicle because of the complexity and risk of the defect, leaving me stranded. General Motors has refused to take responsibility, and the BBB AUTO LINE denied my case due to mileage, but the defect itself is unrelated to mileage or normal wear. This is a manufacturer defect that creates a safety hazard for me, my family, and other drivers on the road. What I’m Requesting: I am asking NHTSA to investigate this issue with GMC Sierra models, as these engine defects make the vehicle unsafe to operate and could lead to accidents if the engine fails while driving. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

My 6.3l v8 Started having a slight misfire while driving. Took vehicle to a mechanic and was advised to change the spark plugs, changed spark plugs, spark plug wires, and ignition coil packs while still experiencing sudden misfires while driving. Starting to consider the 6.2L L87 collapsing cylinder issue.

For approximately the last year (2024-2025) my 2020 GMC Sierra 1500 AT4 with the 6.2L engine has had noticeable ticking, knocking, and unprovoked shaking upon start up and idle. The pickup has stalled out at stop lights and intersections in the past, posing risk. In June (2025) the pickup was taken to a certified mechanic for inspection who suggested possible lifter or valve failure. The vehicle exhibits a persistent ticking sound from the engine, which I believe may be related to lifter or valve issues, similar to those reported in lawsuits against GM for 2019-2024 models and the recall for 2021-2024 models (NHTSA Recall ID: 24V-676). This ticking occurs regularly, including at approximately 54,500 miles, and raises concerns about potential engine failure or sudden loss of propulsion, which could be hazardous, especially at highway speeds. I have noticed approximately 2 quarts of engine oil usage per my last 2 oil changes (roughly every 6,000 miles). I recently had taken the pickup to a local GM dealership where they informed me that I am not longer covered under warranty and the recent recall is not applicable. I was advised to “keep and eye on it, and get a AAA membership”. I am aware of at least 10 class action lawsuits against GM for similar engine issues in vehicles like mine, suggesting a widespread defect. These issues, combined with the potential for engine failure or impaired vehicle control, warrant investigation to ensure driver safety. I have records of the ticking sound and can provide further details if needed. I am willing to cooperate with NHTSA for inspections or further documentation.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving with cruise control mode set at 55 MPH, the vehicle independently accelerated to 98 MPH, and then the vehicle lost motive power. Additionally, the contact stated that the vehicle had failed to turn off upon pressing the Engine Start/Stop button. No warning light was illuminated. The vehicle was able to restart and was taken to a local dealer to be diagnosed, but the cause of the failure could not be determined. Additionally, the contact noticed that water was leaking inside the vehicle through the rear window on rainy days. The contact stated that the infotainment screen had failed to turn on as intended on some occasions, and the screen had displayed a rearview camera image while the vehicle was in drive(D) on other occasions. The contact stated that while driving at various speeds, the transmission made an abnormal sound, and the RPMs failed to decrease as intended, but suddenly dropped while decelerating. Additionally, the contact stated that the headlights, the fuel pump, and the main pulley were replaced at the local dealer. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 250.

My GMC had a terminal engine failure around 5/3/25. This disengaged the ESC, parking brake, and driver assist abilities as well as making the truck undrivable. GMC service diagnosed the truck needed an entire new engine. The repair took over 2 months to complete and now that I have the truck back, the adaptive cruise control is not working.

Check engine light came on. Cooling fan for engine running none stop. Reduce power mode from engine. Took to dealer, said it’s the coolant control valve. Dealer said the part is on back order and don’t know when they will get it in. Looked up the issues and sounds like many people are having the same problem with the 3L diesel from GMC. These people reporting the same thing and having to wait months for the part. My truck was just out of warranty by 200-300 miles

On June 19th, 2025, I was driving to work when my truck began to lose power, and the check engine light came on. The error on the display is Loss of Engine Power. I took it immediately to Oreilly's so they could run the free engine light check. When they got the report, the employee was amazed that there were over 45 problem codes showing up. As I drive the vehicle there is a pull back from the engine before it starts to pick up speed. On braking as well there is a little kickback before it comes to stop. It takes more foot pressure to pick up speed. The Truck using up more fuel because of this issue. I took the truck to a local certified mechanic, and he ran the diagnostics as well and it came up with the over 45 problem codes as well. His recommendation unfortunately was to take into the dealership so they could check it and see if they have a solution for this engine malfunction and error codes.

Engine overheating at 50,000 miles. Temp would intermittently jump up to 230plus degrees while driving. Radiator replaced per dealership diagnosis. Issue still happening.

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal knocking sound coming from the engine compartment before the vehicle lost motive power with the check engine warning light illuminated. The vehicle was towed to the residence. The dealer was contacted; however, the vehicle was not diagnosed or repaired. The dealer referred the contact to the manufacturer for further assistance. The manufacturer was made aware of the failure. The approximate failure mileage was 138,000.

I own a 2020 GMC Sierra 1500 with a 5.3 liter engine..... My engine lifters failed at 105,235 miles.... Lifter broke and damaged the Cam Shaft to a point that required full engine replacement costing me $10,800. When I asked GM for help, they denied because I went to a local repair shop with certified mechanics. I believe GM is fully aware of this problem and they are ignoring I think GM should pay for at least half of my repair bill. Thank you!

Engine failure/ lifter issue with no prior warning. Driving down the road vehicle suddenly lost power and error message appeared. The vehicle was inspected by GM dealer and extended warranty company in late 2023. We no longer own this vehicle

I took my 2020 GMC Sierra 1500 to the dealership after Cylinder #5 seized while driving, and I was forced to replace the entire engine. At the time, I contacted the dealer and was told there was no recall related to this issue. However, I have since learned that GMC has issued a recall for similar engine problems affecting 2021–present Sierra 1500 models, but not for my 2020 model year. I believe this issue may be related and would like further investigation and consideration.

My engine slowed down on the interstate. My steering wheel was visibly shaking and I lost the steering access control. The truck threw an Cylinder 6 error code. At the mechanic, they identified that at least one of my camshaft lifters had failed. If I had continued to drive my vehicle, the engine block would have eventually locked up.

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal knocking sound coming from the engine compartment and the vehicle then failed to exceed 30 MPH. No warning lights were illuminated. The vehicle was taken to the dealer, who were unable to determine the cause of the failure. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); but the VIN was not included. The manufacturer was notified of the failure, a case was opened, and the contact was referred to the NHTSA Hotline for assistance. The failure mileage was 90,000.

Vehicle currently has 104K and needs a 3rd engine. The same issue happened to the second engine as the first. While Driving the engine just stop working. They say it is a problem with the camshaft. Metal gets into the transmission and that also has to be replaced. A vehicle engine should not just stop working! Especially on an interstate. GMC refuses to add this engine to the recall list. However, I don't understand how the safety of families can continue to be placed in jeopardy.

Transmission has slipped and shuddered multiple times. We have had it diagnosed at gmc dealership and our mechanic, advising that it is 8L90 transmission failure. It will slip to lower gear abruptly, causing for possible safety issues especially on the highways.

Lifter failure at around 102-103k miles, was doing a random misfire and transmission studder ( due to the dfm system activating, cutting down cylinders to save fuel while driving, this was happening since approx 59k miles, dealership and gm was aware of it and they said it was normal, but that normal misfire turned into a failed lifter causing misfire and studder. I ended up replacing the lifters myself put solid lifters and a new camshaft that would eliminate the dfm system and studder, ran good no studder and random misfire, and now my crankshaft or oil pump is bad which I will remove motor to furthermore inspect. I’ve read forums and stuff where people would get a lifter job done and then soon after couple thousand miles later the motor goes bad. The 5.3 motors have bad crankshafts, oil pump and lifters just like the 6.2lt motors. After the lifter and cam repair, it ran good for couple thousand miles shortly after My gmc threw an “oil pressure low turn off vehicle code”, turned off vehicle immediately and checked oil, verified oil was good. Gm will not cover it because of it being way out of warrenty when I had issues with random misfire around approx 70-78k miles, and to note that my cat converter went back when lifter failed aswell. Also to note that when the lifters fails it throws a speed reduced to 55 mph, traction off, steering assist reduced, and brakes reduced, this is a safety hazard and also it will drain the battery and cannot start it if you pull over on the side of the road and turned it off and on again to make it back home.

Misfire alerts causing major motor repairs

My 5.3 engine spun a bearing on the crank. Same exact problem the 6.2 got recalled for. Now if I put a used engine in it’ll cost me around $6,000.

Driving at freeway at 65mph, suddenly is air noise like air conditioning blows air at high fan speed, than the dash info shows (Engine Power is Reduce) try to accelerate to pull out of lanes, and it did not, keep losing speed, as slowly move lanes to the right of freeway, and then exit.. This is the second time of this incident, first time under warranty, dealer fix transmission first time, then two months later, the tansmission was replace wit a newone, now is passed warranty, had the car taken to dealer, they gave me and estimate of more then $10,000 to fix the vehicle, this happen on May 21, 2025...

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle jerked while accelerating and while coming to a stop. The check engine warning light was illuminated. The vehicle was taken to the dealer, but no cause of failure was found. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 65,000.

Engine started rough idle, reduced power, poor acceleration, ticking and knocking noises, and a check engine light and a few other lights came on the dash. Safety was not a risk at time of incident. Problem has NOT been diagnosed yet BUT have done a ton of research and it’s all leading towards lifter failure/misfire issues. No warning lights or symptoms prior to sudden problems.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while attempting to start the vehicle, the vehicle vibrated abnormally. The engine warning light was illuminated. The contact stated that on another occasion, while driving at an undisclosed speed, there was an abnormal knocking sound coming from the engine. There was no warning light illuminated. The vehicle was towed to the dealer; however, a cause for the failure was not found. The vehicle was not repaired. The failure recurred and the contact stopped driving the vehicle. The manufacturer was not made aware of the failure. The failure mileage was approximately 110,000.

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 5 MPH, the vehicle made an abnormal popping sound. The check engine and the ABS warning lights were illuminated. The messages "Parking Brake Service" and "ESC Service" were displayed. Additionally, the contact stated the vehicle experienced a reduced fuel range. The vehicle was taken to the dealer, where it was diagnosed that the lifters had fractured, causing damages to the engine. The dealer determined that the engine needed to be replaced, and the part was ordered. The vehicle was not repaired. The contact related the failure to NHTSA Action Number: PE25001 (Engine, Engine and Engine Cooling). The manufacturer was notified of the failure. The failure mileage was approximately 80,100.

Motor failed with no warning, motor was replaced at a GM dealer for $12,000. Mechanic stated he believed it was a main bearing failure. Not under warranty.

On [XXX] at around noon I was driving my 2020 GMC Sierra northbound on [XXX] 26 miles north of Moab Utah. My truck died and I attempted to coast to the next passing lane but did not make it. The shoulder was about 3 feet wide and then had a steep drop off. I pulled over as far as I could but the majority of my truck and trailer was still in the only northbound lane. The northbound traffic was forced to cross over the double yellow into the oncoming southbound traffic. The concern was getting rear-ended by northbound traffic behind me or a head-on collision with the northbound traffic veering into southbound traffic. I made several attempts to restart the truck and the dash just goes blank with no attempt from the starter. We waited for a tow-truck and about an hour into this wait Utah Highway Patrol arrived and parked behind us with his lights on warning traffic from both directions. There were no precursors to this failure or notifications. I didn’t even hear any noises. There was no physical damage or any leaking fluids. It just quietly stopped. John Elway Chevrolet informed me the bearings failed and the engine seized. I wanted to keep the core for evidence due to learning about the numerous catastrophic failures of the L87 engine I had. Keeping the seized core was going to cost me double the cost of a rebuilt one ($7000). When I asked the service Manager, Ben why its twice the cost? He said, “GM doesn't want you keeping the core and they can set whatever price they want .” I have had this truck since it was new (6 miles) and noticed unusual oil consumption early on. I would never make it to the next oil change without having to add oil, even with the very first oil change. I inquired about this with the dealer and told this extreme oil consumption was normal and given Bulletin 01-06-01-011M. I did not involve my insurance because they do not cover engine failure. I paid $12,653.97 for a remanufactured long block. Of that was $2469.93 was for parts not need INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I was driving on the frontage road that enters the freeway when then engine suddenly failed and stalled. It lost power and seemed like it was misfiring. All the warning lights on the dashboard came on as this happened but there were no warnings lights, messages, or symptoms before this happened. The sudden loss of power posed a risk to my safety because it could have caused a crash or left me stranded. I had my vehicle towed to the Freeway Chevrolet dealer in Chandler, AZ where they inspected the vehicle and confirmed the engine had a camshaft and lifter failure.

Engine Lifters failure. Problems with Dynamic Fuel Management System

The contact owns a 2020 GMC Sierra 1500. The contact stated that occasionally while driving at various speeds, several unknown warning lights remained illuminated, and the vehicle lost motive power. The vehicle was taken to a local dealer to be diagnosed, and the contact was informed that DTC: P0016 was retrieved, and it was confirmed that the engine had failed and needed to be replaced. The vehicle was not repaired. The contact referenced NHTSA Campaign Number: 25V274000 (ENGINE AND ENGINE COOLING). The contact expressed a concern that the remedy was the same engine that was prone to failure. The manufacturer was notified of the failure. The approximate failure mileage was 150,000.

1) Complete Engine Failure. Vehicle is no longer is in possession for inspection but pictures and video can be provided. 2) My Truck stalled at 70 MPH going down the interstate. I was lucky to be driving in the right lane to glide to a complete stop. This could have been way worse, not just for myself but for others. 3) Shortly after the loss of propulsion on the interstate. The engine started knocking very loud and I brought it into Boucher GMC of Brookfield. After about a week, the conclusion was I needed a new Engine. The Bearings, camshaft, rods and other components within the engine were damaged. The dealership said it was because of Bad Oil. 4) Parts were inspected and Dealership provided pictures. Not sure what they did with the junk parts. 5) I initially brought in the vehicle where it was purchased at Kunes of Stoughton WI for a Check engine light that read a P06DD error code at 56472 miles on the truck. They performed a software update and sent me on way. Since then, I was dealing with a on and off engine light which eventually brought me to a engine replacement at about 70,000 miles. None of this was covered under warranty and I had to pay for all of this out of pocket. In the events of all this. GMC had my truck for about 3 months. I had to purchase another vehicle because it was cheaper then renting one, GMC didn't have a loaner I could use. I could not perform my everyday work tasks besides getting to and from work, because I did not have a truck to carry my everyday work tools. Now understanding the full impact of this faulty engine and that I could have done harm to others or my self, has me worried about driving a GM vehicle. After I received the new engine, approximately 2000 miles later, The new engine, not rebuilt started making a knocking noise, only to find out, it was the same issue after bringing it to the dealership. No engine lights or nothing. People should be scared to drive a vehicle with the L87 engine from GM.

Shut off in traffic twice

Engine locked up

3.0 LM2 Duramax engine failed at 91,000 miles. It needs a new engine and they are available with a 2-3 week wait time. The engine failure has been inspected and confirmed by the dealer. No symptoms or check engine lights were on prior to the failure. Problem first appeared 03/2025.

I have had two engine failures within 2 years of buying a new GMC truck. The first occurred at 24,181 miles whereas i found engine failures is an all to common occurrence with these 5.3 liter engines, failures are wide spread, tons of complaints can be found with a simple internet or youtube search. The second engine failure occurred at 45,517 miles, again with lifer falling apart. Several service bulletins have been issues including reworking vehicles on dealers lots to replace faulty components but in my case i had over 16000 miles so they put the same parts in again and did not touch the other side which then failed two years later at in my case both were attributed collapsed lifter. This is a safety concern, there is no indication this is about to occur. The vehicle loses power, shakes, instrument panel lights up with various different warning lights. If you are passing another vehicle and this occurs it can be frightening as you have no idea what is happening and why you are no longer accelerating if you are passing some vehicles. The value of these vehicles is now also diminished, who wants a GM vehicle with two engine failures with 45k miles? No one, because it more than likely going to keep occurring until the engine is damaged beyond repair.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the low oil warning light illuminated even though an oil change had been performed within 1,000 miles. The vehicle was taken to the dealer, who diagnosed a failure with the piston O-rings, resulting in damages to the engine. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Action Number: PE25001 (Engine and Engine Cooling). The manufacturer was notified of the failure but provided no assistance. The failure mileage was 79,000.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while attempting to start the vehicle, the vehicle failed to start. There was no warning light illuminated. The contact pushed the vehicle out of the garage. The vehicle was towed to a dealer where it was diagnosed that the spun bearing had failed. The contact was advised that the engine needed to be replaced. The engine was replaced. The contact stated that recently there was an abnormal sound coming from the engine. The vehicle was not diagnosed or repaired after the most recent failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 40,000.

2020 GMC Sierra "Denali" 6.2L engine with only 64,000 all original well maintained at miles -- NO prior issues no unusual sounds or indications of any issues. Vehicle has had timely maintenance regularly. engine lost power and began shuddering severely. Immediately taken to GM certified dealership upon which charged almost $1600.00 for engine analysis. Diagnosis is cylinder # 5 had lifter collapse which in turn ruined the camshaft. Will have to wait 4 weeks for parts and since GM power train warranty (conveniently) only covers first 60,000 miles the total engine rebuild is out of my pocket. Total price $9,741.11. THIS IS RIDICULOUS AND GM NEEDS TO REPAIR OR REIMBURSE EVERY SINGLE OWNER THAT EXPERIENCES THIS ISSUE IN FULL. I think GM knew about this issues and hopes it will go away but this really pisses me and SHOULD everyone else too.

Second engine failure in 8 months. 1st with 97k miles and last after 15k on a brand new 6.2L engine.

Number 5 cylinder failure. Engined has failed cylinder is scored causing the engine to miss and lock up. The engine which is a 6.2 l87 is now under investigation for a piston failure causing the engine to lockup. The piston and engine issue has been investigated by my local repair shop and I can provide written and bore scope pictures of the failure. Yes the engine light was on the ESC was disabled and needed replaced and the traction control was disabled also the emergency brake was enabled and then failed

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 70 MPH, the check engine warning light illuminated, and the vehicle lost motive power. The contact attempted to restart the vehicle however, the vehicle failed to restart. The contact stated that several nearby drivers assisted with pushing the vehicle off the roadway. The contact stated that the first failure occurred the day after the vehicle was purchased. In addition, the contact stated that the failure had also occurred three times within one week. The vehicle was towed to the dealer where the vehicle was purchased. The vehicle was not diagnosed or repaired by an independent mechanic or the dealer. The manufacturer was made aware of the failure, and a case was filed. The failure mileage was approximately 123,000.

At 59000 miles my lifters were rebuilt on the 6.2 liter engine because of a failure in the 1 and 3 piston. Gm paid for the repairs and then At 79000 miles the motor completely blew resulting in complete failure and seizing the motor and heavy metal chips were reportedly found in oil pan. Gm claimed it was a result of me not doing regular oil changes however I suffer from OCD and I am automotive engineer and my oil was changed early in most cases with my truck. Gm will not take responsibility and at the time they wanted $16k to fix my truck. I was going through a very tumultuous divorce and had to pay atty $34k for that wnd could not pay $16k for a new engine resulting in me having to give my truck back to bank and I have not been able to buy a truck or vehicle since then as it ruined my once perfect credit of 820. It’s changed my life forever and GM should take responsibility. I will never buy another GM product again and my father worked for them my whole life and my family only drove their products.

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 70 MPH, the low oil pressure warning light illuminated. The contact pulled over to the side of the road and noticed that the oil level was abnormally low. The contact added oil to the vehicle and continued driving. The vehicle was taken to Mike's Garage, where it was diagnosed that the valve cover was fractured; however, the part to repair the vehicle was on backorder. The contact related the failure to TSB Number: 22-NA-027. The dealer was notified of the failure and informed the contact that the vehicle was not covered under the TSB. The vehicle was not repaired. The manufacturer was notified of the failure, but no assistance was provided. The failure mileage was approximately 96,000.

The Lifter failure, bent rod, and basically ruined the the cam shaft, the vehicle has had engine replaced and the current engine is now acting up. once again.

While driving our 2020 Sierra AT4 down the highway at 65 mph, the engine suddenly cut out and started sputtering. Every light came on. We pulled off the highway and had the truck towed. Our highly trusted, family mechanic company diagnosed lifter 5 was twisted and stuck, along with another stuck lifter. The cost to replace the engine was one hundred dollars more than repairing the two lifters. They purchased a new engine through Van Chevrolet and were surprised the cost had recently decreased from $7-8k to $3900, to purchase a rebuilt engine. The engine appeared to be new, with the bolt threads unused. The new engine comes with a 3year 100k mile warranty through the dealership. We called GM, they said since we went to another mechanic they would not speak with us.

The engine, while driving down the road, incurred a failure to the pusher rod in the #5 cylinder. This occurred at 6750 total miles on engine. Engine failure was repaired by a dealership. The failure occurred again at 99,500 miles to the same #5 cylinder causing major engine damage leading to the replacement of the engine. Our safety was put at risk as the truck decelerated and began vibrating. The second failure occurred and the engine shutdown. These incidents occurred without warning, Yes, a dealer was involved in both incidents. Only a dealership has been involved. The warning occurred after the failure.

My engine has had continual random piston misfire issues, I have changed the spark plugs, fuel injectors, and cat converter. The vehicle has "dynamic fuel management" (DFM) where four of the cylinders turn off when the load on the engine is low and turn back on when the load is high. A mechanic reviewed the vehicle and determined that all eight cylinders are turning off while driving due to the DFM. When it misfires there is momentary loss of power that potentially puts others at risk. A dealership performed a repair per a Bulletin but the issue was not fixed. The mechanic indicated this is a software issue with the computer update per the Bulletin. I have installed a DFM disabler to prevent DFM from working, don't have misfires, but this is an engineering issue that GM hasn't/won't address.

The engine failed. There was no warning. The truck literally just cut off in the middle of the road. I never saw any lights or there was no symptoms to lead up to this incident.

At 125,000 miles, the CEL came on and the code is P0016, which is for the timing chain has stretched and jumped a tooth. The engine was new in 2019 and in 2021, they redesigned the timing chains due to early failure. The oil pump belt is listed for inspection/replacement at 150,000 miles, but the timing chain does not give any interval for replacement and should easily outlast the oil pump belt to at least 250,000 miles. GM knows that there is a timing chain issue with the 3.0 Duramax LM2 engine and it is costing owners between, $7,800 and $10,000 to repair.

Wife and I bought a truck from Serra Chevrolet on May 28 2024. We drove 180 miles and the engine blew up. Had it towed to another dealership in Louisville Kentucky at that point they replaced the engine. When we picked up the truck we had to pay $16,275.08. We contacted Gm and was told that the selling dealership should have taken it off of being certified pre owned but they didn’t. Was told they know to do it to future vehicles and there is no reimbursement . Gm website still has it listed of have a warranty till December 2025. We had 3 weeks of a truck rental at roughly $1,200.00 per week. Had another rental for another. 3 weeks I have paper work from a local dealer stating it still has warranty which would have covered complete expense of engine work We live in Ohio and had to travel back and forth 6 times. Hope there is some help for us.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving 80 MPH, the vehicle lost motive power and stalled. The vehicle regained power within seconds and the contact was able to continue driving. There were no warning lights illuminated. The contact stated that the failure reoccurred. The vehicle had not been taken to the dealer to be diagnosed or repaired. The manufacturer was made aware of the failure and confirmed that there was no recall on the VIN for the failure. The failure mileage was approximately 50,000.

I have had no issues with my vehicle since I purchased it in July 2022 and keep up with the routine maintenance on it. About 2.5 weeks ago I was driving to work like I normally do and the truck started making a knocking noise and all these sensors lights came on the dash. The alerts were saying to service the parking brake, service ESC, and that steering assist is reduced and to drive with care. The vehicle also started shaking and would not accelerate properly or shift gears. We ended up taking it to the closest GMC dealership and they were in able to diagnose it just by simply hooking it up, they had to fully dismantle the engine in order to diagnose it. They came back and said cylinder number 4 is damaged as well as the lifters and cam shaft. I am no car expert but it is weird that a car that is relatively new and has the maintenance kept up on it should not experience a serious malfunction like this. What is even weirder is my sister in law has a 2020 Chevy Silverado where the almost identical thing just happened to theirs and it too is now in the show as well needing its engine and stuff repaired.

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving and decelerating from 65 MPH to 15-20 MPH to make a turn, the engine made an abnormal knocking sound. The contact was able to drive to the residence. The dealer was notified of the failure. The vehicle was towed to Pechous Repair to be diagnosed. The contact was informed that the engine was blown and needed to be replaced. The vehicle was repaired. The contact later became aware of NHTSA Action Number: PE25001 (Engine, Engine and Engine Cooling); which the contact related to the failure. The manufacturer was not notified of the failure. The failure mileage was approximately 64,298.

On January 8th I was driving when my 2020 GMC Sierra 1500 Denali started to misfire as well as several warning lights blinking. I happen to be a couple miles from the dealership I purchased it at so I drove it straight there. A few days later I was notified it was the lifters that went bad and it would cost $5400 plus tax. This is disturbing since I have only had my truck for a little over 4 years with 68,000 miles on it. After researching the problem it appears that its a common issue and I notices a class action lawsuit for this reason. Since it's not recalled currently I'm stuck covering the invoice. Before the problem happened my truck was driving normal and no warning lights came on. This needs to be investigated so the consumer isn't stuck paying for something that is an obvious GM issue .

I had Engine Failure in June 2024 with roughly 50,000 miles. I was getting on I75 North in Auburn Hills, MI, when I heard a loud pop. The vehicle began shaking violently with a loss of engine power warning displayed, loss of oil pressure displayed followed by 2 successive limp mode warning. The vehicle would not drive over 25 MPH. Luckily the next exit was only a mile down the road. I was able to drive on the shoulder of the Interstate to get off of the highway. When I parked the vehicle shortly after, I viewed oil spewed all over the engine bay and under the truck. I then waited 4 hours in 95+ heat for a tow truck. The engine was replaced by the dealer with no root cause identified or communicated to me. There were no warning prior to this failure. The vehicle has had over 13 warranty related issues including the DEF heater melting, CAC pump failure, Numerous Exhaust Leaks, NOX and EGR sensors failing, brake control module faults etc.

The contact's son owns a 2020 GMC Sierra 1500. The contact stated while driving at various speeds, the vehicle shut off without warning. The contact stated that the vehicle was restarted and resumed normal operation moments after the failure. The contact stated that the failure recently started occurring more frequently. The manufacturer was notified of the failure and the contact was provided a case number. The contact was referred to the NHTSA Hotline to report the failure. The vehicle was not repaired. The failure mileage was approximately 40,000.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while the vehicle was parked and being driven, the vehicle was shaking violently. There were no warning lights illuminated. The contact stated that the failure was related to Technical Service Bulletin: 22-NA-186. The vehicle was taken to a local dealer, where it was diagnosed that the motor mount brackets needed to be replaced. The vehicle was repaired, but the failure persisted. The manufacturer was contacted, opened a case, and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 100,000.

See attached document for complaint

Vehicle has excessive oil consumption. Within 5000k oil change interval, no oil on dip stick around 3000k miles.

1. Valve Lifter Failure 2. While entering the [XXX] freeway and trying to merge into traffic the engine lost power and I had to swerve and brake to avoid an adjacent vehicle, and freeway traffic had to avoid my slowing down to pull over. 3.Yes, Van GMC in Scottsdale, confirmed lifter failure. 4. Yes, GMC Dealership 5. Absolutely no warning given INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

timing chain failure, timing chain components are available for inspection. Costly premature repair/failure. Could leave occupants stranded in unsafe environment which could lead to death. The vehicle has been diagnosed by the dealership and OEM manufacturer has been notified. There was a warning lamp.

I have a 202 GMC Sierra 1500 with a 3.0 Duramax with 95,000 miles. I have hade 2 glow plugs replaced under warranty and took in for a third glow plug. They stated that the there was a software update that could fix it, but I would have to pay for it. The vehicle has a 100,000 mile warranty and the software update is to fix a powertrain item that is covered under the 100,000 mile warranty. This is also an issue with bad software that disables the remote start. Not sure why I have to pay for this software upgrade to to a GM issue from day 1.

Diesel exhaust fluid heater short circuits due to poor design. This issue occurs multiple times, including after being repaired. The failure limits the trucks capabilities until it is entirely unusable.

A VERY STRONG "AMMONIA" ODOR COMES INTO THE CABIN. THIS HAPPENS WHEN THE DEF FLUID IS GOING INTO THE EXHAUST SYSTEM FOR THE REGEN PROCESS. THE ODOR MAKES PEOPLE INSIDE NAUSEOUS AND DIZZY. MUST OPEN WIDOWS OR STOP AND GET OUT OF THE VEHICLE. OUR GMC DEALER CAN FIND NO CODES OR PROBLEMS WITH THE EXHAUST SYSTEM. WE HAVE ALSO NOTICED THAT THE DEF FLUID HAS GONE DOWN VERY QUICKLY SOMETIMES DURING THIS EVENT. IT IS RANDOM. SOME DAYS NOTHING, OTHER TRIPS 3 AND FOUR TIMES THAT THE ODOR OCCURS. LOOKING ONLINE- THERE HAVE BEEN MANY POST ABOUT THIS PROBLEM.

The contact owns a 2020 GMC Sierra 1500. The contact stated that shortly after refueling while driving under 15 MPH, the check engine and service emissions warning light illuminated. The contact stated that an unknown reset was performed related to TSB: 10173675 (Engine). The vehicle was not yet fully repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 46,000.

Repeated issues with exhaust and emissions components.

Found improperly installed rear seals. The truck leaked oil and had to be towed to gmc dealership in Monahans Texas to be repaired. 1 month later the truck leaked oil again.

Rear main oil seal failure causing truck to lose all oil, leaking all over truck, trail leading to drive and garage; possibility of engine seizing up while driving causing an accident, confirmed by dealer, covered by warrenty, is a known issue, no warning lights, messages, or other symptoms of problem, NHSTA has issued a bulletin for this problem

AT ABOUT 3500 MILES LIFTERS ON TWO CYLINDERS COLASPED. TOOK TO DEALER THAT DEALER HAD THREE WEEKS BUT FIXED IT. 1500 MILES LATER AT 5036 MILES IT HAPPENED AGAIN ON A DIFFERENT CYLINDER. NUMBER 8. THE FIRST TIME IT WAS 3 AND 5. THE FIRST TIME THE DEALER REPLACED ALL 8 CYLINDERS. SO CYLINDER NUMBER 8 WAS NEW AS WELL. GMC HAS SAID THERE IS NOTHING ELSE THAT CAN BE DONE TO FIX THE ISSUE. THE SECOND DEALER SERVICE MANAGER STATES THAT HE WOULD NOT TRUST IT EITHER TO GO ANY LONG DISTANCE . ALSO STATED THAT THEY HAVE PUT 3 SETS IN TO ONE VEHICLE BEFORE. AS AN ASE MASTER CERTIFIED TECHNICIAN I FIND THIS DISTURBING. I ALSO WAS A GMC,PONTIAC, OLDSMOBILE MASTER TECHNICIAN. THIS IS UNEXCEPTABLE FOR GM TO THINK THIS IS OK TO TAKE PEOPLE'S HARD EARN MONEY AND NOT FIX THERE ISSUES OR MAKE IT RIGHT. I OWNED A 2014,2016,2018 SILVERADO'S THAT HAD NO ISSUES WHAT SO EVER. TO MAKE THINGS WORST GMC ROAD SIDE ASSISTANCE FORGOT ABOUT THE TRUCK BROKE DOWN IN 7 DEGREE WEATHER WITH 35 MILE AN HOUR WINDS. FOR OVER 24 HOURS AND SEVERAL CALLS BACK TO FINALLY GET A SUPERVISOR TO SPEAK TO. TWO DEALERS SAY THAT IT IS UNACCEPTABLE EXCEPT THE CURRENT DEALER THAT IS DEALING DIRECTLY WITH GMC. ANYONE CAN DO A SEARCH ON GM TRUCK LIFTERS COLLAPSING AND YOU IMMEDIATELY OVERWHELMED WITH INFO. IT IS ALSO DISTURBING THAT A DEALERSHIP SERVICE MANAGER SAYS WE COULD PUT A NEW ENGINE IN AND THE SAME THING COULD HAPPEN. THAT TO ME IS POOR QUALITY CONTROL AND POOR CUSTOMER SERVICE. I HAVE ALWAYS BEEN A GM ENTHUSIASTS BUT THIS WILL BE MY LAST ONE. HORRIBLE CUSTOMER SERVICE AND DO NOT BUILD A GOOD PRODUCT OR STAND BEHIND IT. GM SHOULD BE ASHAMED OF THERE FALL FROM GRACE. THIS ALL HAPPENED JUST DRIVING ONCE TO WORK AND ONCE HAULING A ATV ON A TRAILER.

WITHIN 3 MONTHS (<4000 MILES) FROM PURCHASE VEHICLE BEGAN SPUTTERING WITH HESITATION, AND TICKING NOISE FROM ENGINE WHILE IN MOTION FOLLOWED BY MULTIPLE ALERTS POSTING ON DRIVER DISPLAY. VEHICLE DISPLAYS LOSS OF POWER, AND STRUGGLES TO KEEP UP WITH TRAFFIC. CHECK ENGINE LIGHT FLASHING FOLLOWED BY CONSTANTLY STAYING ON, SERVICE ESC SYSTEM ACTIVATED, SERVICE PARKING BRAKE, AND STEERING ASSIST REDUCED DRIVE WITH CAUTION LIGHTS ALL ACTIVATED DURING THIS EPISODE. DEALER WORKED ON VEHICLE ENGINE ( AND COMPLETED ON OR AROUND 1/08/2021), AND REPLACED LIFTERS, AND OIL CONTROL VALVE. ON 01/13/2021 NOTICED THAT VEHICLES LANE KEEP ASSIST IS NOW WORKING SPORADICALLY, WILL NOT ACTIVATE CONSISTENTLY WHEN VEHICLE VEERS OFF THE PROPERLY MARKED LANES ON HIGH-WAY/ROADS, AND INCONSISTENTLY ALERTS DRIVER WHILE IN MOTION. THE LANE KEEP ASSIST IS SUPPOSE TO CORRECT STEERING, BUT THIS DOES NOT HAPPEN CONSISTENTLY. THE COLLISION ALERT SYSTEM DOES NOT ACTIVATE OR WORK CORRECTLY. NOTICED WHILE DRIVING THAT VEHICLES IN FRONT ARE NOT DETECTED CORRECTLY, AND INFORMS THE DRIVER THEY ARE WITHIN SAFE DISTANCE (GREEN THIS SUDDENLY CHANGES TO YELLOW). IN ADDITION WHEN VEHICLES IN FRONT APPLY BRAKE, THE COLLISION ALERT SYSTEM DOES NOT ALERT AS IT IS SUPPOSED TO, IT STAYS IN GREEN EVEN AT EXTREMELY CLOSE RANGE. SAFETY MECHANISMS DON'T APPEAR TO WORK CORRECTLY, AND DETECTS ITEMS THAT ARE NOT PRESENT. NOTICED THAT VEHICLE DETECTS LANES EVEN ON UNMARKED ROADS, AND THE FRONT PEDESTRIAN ALERT SYSTEM ACTIVATES SPORADICALLY EVEN IF NO PEDESTRIANS ARE IN FRONT OF VEHICLE WHILE DRIVING. CONCERNED ABOUT SAFETY FEATURES LEADING TO HAZARDOUS DRIVING CONDITIONS.

THE ENGINE FAILED AT 5100 MILES AND IS CURRENTLY BEING REPAIRED BY THE DEALERSHIP. I REQUESTED A NEW CAR REPLACEMENT.

TL* THE CONTACT OWNS A 2020 GMC SIERRA 1500. THE CONTACT STATED THAT THE VEHICLE PUSH START BUTTON AND KEY FOB FAILED TO START THE VEHICLE ON FIRST ATTEMPT. THE CONTACT STATED THAT THE VEHICLE STARTED AFTER SEVERALS ATTEMPTED. THE CONTACT STATED THE FAILURE OCCURRED INTERMITTENTLY. THE CHECK ENGINE WARNING LIGHT ILLUMINATED. THE CONTACT STATED THAT ON HIS WAY TO MCKENZIE BUICK-GMC DEALER, 6500 CAROLINE ST, MILTON, FL 32570, THE CHECK ENGINE WARNING LIGHT WAS NOT ILLUMINATED, THE VEHICLE WAS DIAGNOSED AND THE CONTACT WAS INFORMED THAT A FAILURE CODE WAS NOT FOUND. THE VEHICLE WAS NOT REPAIRED. HOWEVER, THE CONTACT CALLED BACK THE SAME DEALER AND INFORMED THEM THAT THE FAILURE RECURRED. THE VEHICLE WAS NOT YET TAKEN BACK TO THE DEALER. THE MANUFACTURER WAS NOT MADE AWARE OF THE FAILURE. THE FAILURE MILEAGE WAS APPROXIMATELY 86.

VEHICLE EQUIPPED WITH L87 6.2L. AT 197 MILES ENGINE SUDDENLY CEASED OPERATING AND WOULD NOT RESTART. THIS OCCURRED WHILE STOPPED ON PRIVATE ROAD. VEHICLE HAD TO BE TOWED TO DEALERSHIP WHERE THEY FOUND P0300 AND DIAGNOSED BROKEN #4 CYLINDER EXHAUST VALVE SPRING.

RUPTURED OIL COOLER LINE. DRAINING THE ENGINE OF OIL AND CAUSING LOCK-UP. *TR

ENGINE LIKE KEEPS COMING ON. CODE READING THE KNOCK SENSOR NEEDS TO BE REPAIR. SENSOR HAS BEEN REPLACE TWICE IN THE PAST THREE MONTHS. *TR