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2021 Toyota Redundant Sienna Transmission Problems

7 owner-reported transmission complaints from NHTSA data

7
Complaints
2
Crashes
Feb 2025Sep 2025
Date Range

Data sourced from NHTSA public database. For informational purposes only. Always consult a qualified mechanic.

Owner Complaints (7)

criticalPOWER TRAIN
Filed: Sep 2025

Your 2021 Toyota Sienna Hybrid experienced a sudden engine failure while driving—a low oil pressure warning appeared, the engine lost power and went into limp mode, and then a connecting rod broke through the engine block, causing complete engine failure and leaving metal debris in the engine compartment. Before this happened, you noticed rough idling and slight shaking when the engine switched from battery to gas power after sitting, but the van drove normally otherwise despite regular maintenance. The repair will require complete engine replacement or extensive engine block repairs.

NHTSA #: 11687704
mediumPOWER TRAIN,ENGINE,FUEL/PROPULSION SYSTEM
Filed: Jul 2025

Your Sienna is making unusual sounds from the engine or transmission area. Additionally, two rubber seals on your minivan keep warping and failing—Toyota applied tape as a temporary fix, but it came off again. Your back door is misaligned, and the passenger sliding door often won't close properly on the first try, requiring multiple button presses. A permanent repair will likely involve replacing the failed rubber seals, realigning the doors, and diagnosing the source of the engine/transmission noise.

NHTSA #: 11675599
mediumPOWER TRAIN,SERVICE BRAKES
CrashFiled: Apr 2025

When pulling into a shopping center parking space, my mother applied the brakes to slow down, but the vehicle seemed to surge and hit the car in front. It then surged again and pushed that car into another. No airbags deployed, and no one was injured, but someone could have been hurt either by the van itself or one of the other 2 vehicles. The dealer is scheduled to look at the vehicle, but stated on the phone that they "hadn't heard of this happening". There were no warning lights showing. My daughter stated that after the impact, she looked at my mother's feet, and her foot was clearly on the brake. I looked on the internet later, and found several threads of people complaining about their Toyota Sienna hybrids doing similar things.

NHTSA #: 11656450
mediumPOWER TRAIN,ENGINE
Filed: Feb 2025

Turned on my minivan to begin backing out of the driveway when it began violently shaking and exploded. Was not due for an oil change, was not low on oil, passed an engine inspection 5 days prior. 2 holes through engine block caused by either connecting rod or piston

NHTSA #: 11640756
mediumPOWER TRAIN,SERVICE BRAKES
Filed: Sep 2024

-Multiple instances recently of feeling like the car was accelerating or lurching forward lightly while I was braking - thought I was going crazy. Today however, the car very clearly lurched forward while I was braking coming into an intersection with my kids in the car. Checked my foot on the pedal, mats, etc. Will be taken to dealer on earliest appointment they have in 7 days. -If there was a car coming through that intersection, my family and I could have been T-boned due to the unexpected acceleration. -There are no warning lamps or messages active in the vehicle. -Symptoms likely started a few months ago, but the most severe instance was today, 9/16/2024. I finished driving my kids to soccer and while there I googled this and called my dealer. Apparently this is a known issue? -How can Toyota not notify owners of this serious issue? There needs to be a recall immediately. This is my family vehicle that we bought new just a few years ago, this is dangerous and absolutely unacceptable.

NHTSA #: 11614935
mediumPOWER TRAIN,ENGINE,FUEL/PROPULSION SYSTEM
Filed: Mar 2024

About 25% of the time when I come to a stop and I am breaking, the car surges forward slightly. At first, I thought it was the way I was driving or the fact that it is an EV vehicle, which I had not driven before, but overtime it seems it is just the way the car operates. Others in the car have felt it happen as well as I have come to a stop sign or stoplight. I have not bumped into another car or anything but feel that that could happen if this is not corrected.

NHTSA #: 11578332
mediumPOWER TRAIN
CrashFiled: Mar 2022

The contact owns a 2021 Toyota Sienna. The contact stated while driving approximately 65 MPH, the vehicle would jerk and swerve to the left or the right making the vehicle difficult to control. The contact stated no warning light was illuminated. The contact stated that after decelerating the vehicle became controllable. The contact was able to drive to his destination. The contact stated that he had experienced the failure on three separate occasions. On the last occasion, while driving 70 MPH, the contact lost control of the vehicle and the vehicle ended up in the median striking the metal bars in the median. The air bags did not deploy. The contact did not sustain any injury and medical attention was not needed. A police report was filed. The vehicle was not drivable. The contact towed the vehicle to a tow lot. The vehicle was not diagnosed or repaired. A dealer was not contacted. The manufacturer had not been informed of the failure. The failure mileage was approximately 10,000.

NHTSA #: 11454662

Other 2021 Toyota Redundant Sienna Issues