2020 GMC SIERRA 1500 Complaints

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.

I am writing to formally express my dissatisfaction regarding a significant safety and reliability issue with my 2020 GMC Denali. Specifically, the vehicle is experiencing premature wear and imminent failure of the front ball joints. I expect the suspension components of a premium Denali-trim vehicle to last significantly longer than the 37,061 miles currently on my odometer. Industry standards typically place the lifespan of these components between 70,000 and 150,000 miles. Technical Details of the Failure: The vehicle is currently exhibiting the following symptoms of accelerated ball joint degradation: •Excessive Vertical and Lateral Play: Inspection reveals play in the right lower ball joint that exceeds the manufacturer’s maximum allowable wear specifications. The left lower Ball Joint is starting to have a small amount of play, according to the technician

My 2020 GMC Sierra 1500 experienced a premature transmission failure consistent with GM’s known 8-speed transmission defect. My safety and the safety of others were put at risk if/when the transmission occurs a temporary lockup which can/will cause the vehicle to stall on the highway, and potentially create a minor/major automobile incident if vehicle stalls. The vehicle was taken to dealership Capital Chevrolet Montgomery, AL where dealership technician diagnosed/confirmed the issue along with pictures of internal transmission failed components as well as recommended resolution for fix. The vehicle has been inspected by my out-of-pocket expense extended warranty company Endurance Warranty Services sub-contracted repair claims adjuster. No warning lamps, vehicle messages, or other symptoms of the problem prior to the failure were noticeable; the vehicle had multiple diagnostic scans prior to original sale and after sale to present no issues or trouble scans. the first issue appeared or was noticeable 12/08/2025. GM has refused action by asserting warranty expiration despite widespread knowledge of this defect. The vehicle has been out of service since December 8, 2025.

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, 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.

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.

Back window leaks down onto electrical compents and causes mold behind rear seat, plus staining mold on headliner

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.

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.