2020 Gmc Sierra 1500 Body & Structure Problems
9 owner-reported body & structure complaints from NHTSA data
Data sourced from NHTSA public database. For informational purposes only. Always consult a qualified mechanic.
Owner Complaints (9)
Water is leaking into your truck through the back window frame due to a faulty seal, damaging the headliner, electrical components, and airbags. This water intrusion creates risks of electrical fires, airbag failure, and mold growth that could affect your health. Your GMC dealer confirmed the seal is defective but won't cover it outside the 3-year warranty, and GMC has refused to address the issue. The repair will likely involve replacing the rear window seal or the entire rear window assembly to stop the water intrusion.
Parts you may need:
As an Amazon Associate, MyCarTSB earns from qualifying purchases.
My multipro tailgate on my 2020 GMC Sierra 1500 unlatched while a trailer was attached and backing up said trailer. The trailer jack post proceeded to buckle the upper part of the tailgate assembly causing extensive damage resulting in over a three thousand dollar repair bill. If the tailgate had released while a child was in close proximity, serious injury may occur. The tailgate has inadvertently released twice in the five plus years I have owned it, the first time as I was traveling down a highway at over 60 mph. This could have endangered a vehicle to my rear if cargo had been released on to the road. I have reached out to a local dealership for repairs and assessment, no real way of troubleshooting something that has happened twice in five plus years. The scan did not show any codes. the info center does notify you if it is released but not before it takes place and after the fact may be too late in some circumstances as it was during the second occurrence. There has been a recall on 2500 and 3500 models with the exact same tailgate but not the 1500 models. 820K vehicles affected but not on the 1500's.
Had water leaking into cab of truck. First incident they stated it was a rear window seal and it was "repaired" under warranty. Second incident I was advised it was body panel separation where the cab roof and side body seam was leaking. It was repaired by sealing with "body seam sealer." I later read these repairs should have been welded. This was after the warranty expired and I had to pay for it. I then read on the Silverado/Sierra forum this repair should have been a weld not just "glued" is this a safety issue?
Tailgate opened on highway with cargo in bed. Also tailgate opens randomly when parked. This has happened many times, creating very dangerous and unexpected situations Numerous contacts to the manufacturer have been unsuccessful in getting the hazard placed on recall. Numerous incidents. Keeps happening
Rear window leak causing whole inside back to get soaked. Have paid hundreds of dollars to have sealed didn’t work. New window didn’t work it still leaks. It’s going to cause interior to mold and body to rust. Dealership and glass business both say it’s body issue and they have seen many GMC and Chevrolets with this issue. Google show 1000s with same problem.
GM refuses to fix a known design flaw in the back sliding glass frame on 2020_24 gmc sierra trucks. This issue will generate toxic mold as large quantities of water enter the cabin and can be extremely harmful for certain individuals allergic to mold. GM knows about this issue and tried to secretly advise techs via TSB 18-na-383 to apply sealant on the frame and if customer returns to replace frame. However they do not want to do this outside the 3 year warranty. The back glass on a truck is not a serviceable item.
Rear Sliding Glass window frame has cracked and allows water to enter the cab of the vehicle. Yes this is available for inspection. The water entering the cab of the vehicle can create mold from moisture build up if left untreated. I was able to have the dealer service center confirm the issue noted in [XXX] but they were unable to repair it as it is outside of warranty. I was able to have an independent 3rd party glass company confirm that it was indeed a manufacturers defect with a cracked housing and not an issue with sealant around the glass itself. No warning lamps or other indications other than water in the back seat of the vehicle. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
Rear Window Leaks due to failed sealing at the factory. If not fixed will ruin interior components and possibly rust. Yes No No
The back window leaks, I brought it in they told me it wasn't warranty so I paid to have it fixed. Still leaks.