Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2020 GMC Sierra 2500 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2020 GMC Sierra 2500. The contact stated while driving 63 MPH, and towing a 15,000 lb. 5th Wheel RV, the contact heard the rear wheels make an abnormal squealing or chirping sound. The contact stated that the front end of the vehicle was pulling to the right. The contact adjusted the steering wheel to the left to compensate. The contact stated that the vehicle was losing motive power. The contact stated that the drive(D) symbol was flashing on the instrument cluster. The contact depressed the accelerator pedal; however, the vehicle failed to respond as intended. The contact exited the highway and stopped the vehicle. The contact had the vehicle towed to an independent mechanic. The mechanic scanned the vehicle but did not retrieve any fault codes. …
The contact owns a 2020 GMC Sierra 2500. The contact stated that the vehicle was under NHTSA Campaign Number: 24V797000 (Power Train) and the vehicle was repaired. The contact stated that after the recall repair, the transmission started shifting hard. The vehicle was taken to the dealer, and the contact was informed that the transmission module would reprogram and adjust independently. The contact stated that a week later, while driving approximately 45 MPH, the vehicle started to run rough, and the message engine power reduced was displayed. The transmission fault, parking brake system alert, service parking brake, and the check engine warning light illuminated. The vehicle was towed to the dealer, who diagnosed the vehicle and determined that the fuel injector was open, causing high resistance in the connector for cylinder #4. …
The contact owns a 2020 GMC Sierra 2500. The contact stated while driving approximately 65 MPH, the vehicle lost motive power. The contact stated that he had not depressed the brake pedal. The contact was towing a 20-foot flatbed trailer with a load of lumber of approximately 4,000 lbs. in weight. The contact stated there was no warning light illuminated. The contact pulled over with the vehicle still running and attempted to shift into drive(D) and reverse(R); however, the vehicle failed to respond. The contact stated that after shifting into drive(D), several unknown warning lights were illuminated. The contact had the vehicle towed to a local dealer; however, the vehicle was not diagnosed or repaired. The contact researched online and related the failure to NHTSA Campaign Number: 24V797000 (Power Train). The manufacturer was informed of the failure. …
The contact owns a 2020 GMC Sierra 2500. The contact stated while driving 30 MPH, the engine revved while the vehicle lost motive power in the middle of the road. The contact was unable to pull over to the side of the road. The vehicle was restarted but was undrivable. An unknown warning light was illuminated. The contact stated that while the vehicle was being towed, there was a significant amount of fluid leaking onto the ground. The vehicle was towed to Ryan's Repair, where it was diagnosed with a fractured transmission cooler line. The vehicle was not repaired. The mechanic related the failure to an unknown recall. The dealer was not notified of the failure. The manufacturer was notified of the failure, but no assistance was provided because the VIN was not included in the TSB. The failure mileage was approximately 112,000.
The contact owns a 2020 GMC Sierra 2500. The contact stated that while driving approximately 70-80 MPH, the transmission downshifted, and the rear wheels locked up. The contact was able to coast to the side of the road. The contact was unsure if a warning light had illuminated. The vehicle was towed to the dealer, where it was diagnosed and determined that the transmission had failed and needed to be replaced. There were metal shavings found mixed in with the transmission fluid; however, the vehicle remained with the dealer unrepaired. The contact was informed by the dealer that the warranty had expired, and the vehicle could not be repaired. The manufacturer was notified of the failure but declined to assist in covering the cost of the repair. The failure mileage was approximately 166,000.
The contact owns a 2020 GMC Sierra 2500. The contact stated while driving at an undisclosed speed, the accelerator pedal was depressed, and the transmission jerked. The contact stated that the transmission was skipping gear while shifting. The check engine warning light turned on and off. The contact received notification of NHTSA Campaign Number: 24V797000 (Power Train); however, the part to do the recall repair was not yet available. The local dealer was contacted. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The failure mileage was approximately 114,000. VIN tool confirms parts not available.
The contact owns a 2020 GMC Sierra 2500. The contact stated that while her husband was driving 30 MPH, the rear wheels locked up and the vehicle skidded to a complete stop. No warning lights were illuminated. The vehicle was towed to the dealer, who diagnosed a failure with the transmission. The contact was informed that the transmission had imploded and needed to be replaced. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Campaign Number: 24V797000 (Power Train); the VIN was included but the vehicle had not been repaired. The manufacturer was not notified of the failure. The failure mileage was 125,000.
What component or system failed or malfunctioned, and is it available for inspection upon request? - Transmission Valve Body resulting in a P0700 & P0747 code. Yes currently installed in vehicle. How was your safety or the safety of others put at risk? - When the vehicle goes into a limp mode to protect the transmission and rear-wheel lock up, the truck shuttered and hard downshifted. Speed limit is restricted to 5th gear only. I've been instructed by GM to continue driving and using the vehicle until the problem happens again, knowingly putting myself and others at risk on a second failure that could happen at any time. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes this is a common problem with a recall #N242454440, NHTSA 24V-797. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? …
There is an issue that is causing the batteries to die. This in return causes the Vehicle to go into Limp home mode with no warning. The "issue" was supposed to be resolved by the Dealer in March 2022. The resolution was that one battery was bad. The vehicle is equipped with two batteries. Each of which is sufficient to run the vehicle. A single battery failure should not have caused the truck to have a power limitation. Furthermore the issue was not resolved and General Motors and the Local dealership refuse to continue to work on the issue. This is even after filling complaints with BBB. As of November 2022 the issue has cause both batteries to go bad. The dealer has refused to work on the vehicle and it has been out of service for more than 30 days. Secondary issue. …
While driving vehicle flashed engine power reduction signal and then the emergency brake automatic feature came on abruptly. Fortunately, I had been able to slow down after the reduced power, but if I wouldn't have quickly reacted to that, I think the emergency brake system would have caused a safety issue. Now. The vehicle is incapacitated. There were two recalls that describe this exact situation on the same year and model of truck, but my VIN number did not fall. Under that recall. The recall was for the sensor and then the second recall was because the first recall didn't correctly fix it. But the details of the faulty sensor are exactly what happened to my truck. So it sounds to me like they had more problems than just the recall that they acknowledged but they have not expanded it. My quest is to have them expand the recall to all of the vehicles that had the same problem.
Related recalls
Power train › Automatic transmission › Control module › Software
General Motors, LLC is recalling certain 2020 Chevrolet Silverado 2500, 3500, GMC Sierra 2500, 3500, and 2020-2022 Chevrolet Silverado 1500 and GMC Sierra 1500 vehicles that may have been repaired incorrectly under recall 24V797. The transmission control valve may fail and cause the rear wheels to lock up.
Remedy: Dealers will inspect the vehicles and update the transmission control software, free of charge. Owner notification letters were mailed March 6, 2026.
Power train › Automatic transmission › Fluid/lubricant › Valves/valve body
General Motors, LLC (GM) is recalling certain 2020-2022 Chevrolet Silverado 1500, 2500, 3500, GMC Sierra 1500, 2500, 3500, 2021 Cadillac Escalade, Escalade ESV, Chevrolet Tahoe, Suburban, GMC Yukon, and Yukon XL vehicles equipped with diesel engines. The transmission control valve may fail and cause the rear wheels to lock-up.
Remedy: Dealers will install new transmission control module software, free of charge. GM will provide a special coverage program to cover the repair of transmissions that are identified by the remedy software as containing a…
Transmission complaints in other Sierra 2500 years
Frequently asked questions
How common are transmission problems on the 2020 GMC Sierra 2500?
NHTSA has 24 complaints about the transmission & drivetrain of the 2020 GMC Sierra 2500, 31% of the model year's 78 complaints.
Is there a recall for 2020 GMC Sierra 2500 transmission problems?
Yes — NHTSA recall 26V-083 (software, Feb 12, 2026); NHTSA recall 24V-797 (valves/valve body, Oct 24, 2024). Recall repairs are free at authorized dealers.
At what mileage do 2020 GMC Sierra 2500 transmission problems start?
Half of the complaints with a recorded mileage happened before about 114,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.