*Median odometer reading when the problem happened, where owners gave one. One complaint can name several problem areas.
Power train
My truck has been exhibiting hard downshifting at certain speeds, when the powertrain loads up such as a grade change, and requires a downshift. I have complained about this issue to the dealership as early as 2022, and 33,185 miles. The dealership made me pay for a transmission $388.90 flush which did not resolve the issue. The problem has become progressively worse, to the point where the toll road transponder fell of my windshield during a recent harsh downshifting incident. At the same time there was an existing MIL and derating for a DEF heater and NOx sensor failure, so during a warranty visit I asked that this transmission issue be addressed. On Friday March 13, the dealership called…
Mar 12, 2026Unknown or other
Diesel exhaust fluid tank heater malfunctioned and meted tank and connectors.
Jan 12, 2026Structure › Body
Known defect with 2019 and now 2020 GMC sierra trucks. Design was updated for 2021+ which has corrected the seal failure defect. GM has issued a service bulletin to dealers about how to repair the problem. Back window is leaking water. Defective seal noted by GM. GM is only covering the cost of repair if. Vehicle is still under 3/36 warranty. If outside your warranty cost from dealer to owner is $2500 to $6000. A known design failure GM recognized and took steps to change the design for future. Vehicles but will not stand behind vehicles that have this defect. Would like the cost to the repair fall back to GM to cover. Bulletin # 18NA383 [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF…
Oct 1, 2025Engine
the engine seized at 65mph. available for inspection. was left stranded in a limited access area with no cell service. there was no warning, the engine just stopped at highway speed and would not restart. the problem was confirmed by an independent service center. they couldnt identify which component had failed without a costly teardown. occurred at 112,000 miles, past the 100,000 mile powertrain warranty.
Aug 28, 2025Power train
The contact owns a 2020 GMC Sierra 3500. The contact stated that while driving at an undisclosed speed, the vehicle inadvertently went into LIMP Mode. There was no warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed that the transmission valve body sensor had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline for assistance. The approximate failure mileage was 130,000.
Jul 9, 2025 · 130,000 milesPower trainCrash
The contact owns a 2020 GMC Sierra 3500. The contact stated that while driving at 60 MPH, the rear differential seized, in addition, the contact was hauling a median size tracker on top of a flat bed. The flat bed jackknifed and hit the left side of the contact's vehicle. The vehicle was able to come to a stop. The air bags did not deploy. There was no warning light illuminated. A police report was filed. There were no injuries sustained. The vehicle was towed to a towing yard. The trailer was towed to the residence. The tractor was damaged in the accident. The vehicle was diagnosed by an independent mechanic. The contact was informed that the transmission had failed. The vehicle was not…
Oct 2, 2024 · 108,000 milesStructure
The contact owns a 2020 GMC Sierra 3500. The contact stated that while driving 45 MPH with passengers seated in the rear seats, the passengers became aware that water was entering the vehicle between the window and frame. There were no warning lights illuminated. The vehicle was taken to the local dealer, who informed the contact of Technical Service Bulletin: 18-NA-383. The vehicle was not diagnosed or repaired. The manufacturer was contacted and confirmed that there was no special coverage or warranty coverage on the vehicle. The contact was referred to the NHTSA Hotline for assistance. The failure mileage was approximately 50,000.
Jun 10, 2025 · 50,000 milesTires
LT275/65R20 While driving Westbound on I87/US64/US264 at the on ramp of US64 business at highway speeds, the driverâs side rear tire tread de-laminated from the belts of the tire. Observed the entire tread airborne in rear view mirror. Pulled over to shoulder and observed for damage to other vehicles, no vehicle was hit but drivers did have to make evasive maneuvers to avoid debris. Tire remained at required PSI, thus did not deflate. Drove vehicle ¼ mile to ** exit to look for safe parking. Called AAA and had vehicle towed to residence. No police report filed. Reported incident to insurance agent in the event of a subsequent damage claim by other drivers. Tire was inspected by ** Tire…
Jun 27, 2025
Owner complaints are submitted to NHTSA by the public and are not verified. Shown as filed (NHTSA removes personal details); long reports are shortened.