2020 GMC Sierra 2500 transmission problems

Filed Oct 13, 2026 · Transmission · 107,000 miles · TX

The contact owns a 2020 GMC Sierra 2500. The contact stated that while stopped at a traffic light and making a left turn at approximately 20 MPH, the transmission failed. The vehicle was unable to exceed 10 MPH. The check engine warning light illuminated, and a dinging sound was heard following the incident. The vehicle shifted erratically, jumped gears, and made unusual noises. The contact associated the failure with the federal safety agency Campaign Number: 24V797000 (Power Train). The vehicle was towed to the dealer for diagnosis. The dealer confirmed an internal transmission failure and clutch lockup, with DTC P2732. Additionally, the transmission fluid was burnt and contained metal shavings. The dealer contacted General Motors after informing the contact of the repair costs. The failure mileage was approximately 107,000.

Filed Sep 24, 2026 · Transmission · KY

A dealer "fixed" the P20EE code on this date, then the code came back a week later. Same dealer said they don't have qualified diesel technician, took vehicle to a 2nd dealer 9/22/2025, unable to determine cause of code. On 6/18/2026 same P20EE code came on again, took to dealer, dealer able to perform repairs on 7/30/2026 after ordering the correct parts. No on 9/23/2026 P20EE code is back.

Filed Sep 19, 2026 · Acceleration, Driver assistance · KS

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.

Filed Mar 10, 2026 · Transmission · VA

While driving down a highway doing between 45 and 55 mph the transmission suddenly and completely faulted causing the truck to come to a complete stop. Just enough power to get to the shoulder luckily. The transmission had basically completely blown out, fluid everywhere. The insurance company did not find any comprehensive damage. The entire transmission needs to be replaced. There were no indicators showing any problems, no alerts, no warning whatsoever. Mechanics said there was a lot of metal coming out of the transmission. The truck is currently in a mechanic shop awaiting the new transmission, so at this time it is available for inspection. The safety issue here is that it happened on a busy highway, and the vehicle was no longer drivable so it needed to be towed causing more time spent on the side of the road.

Filed Feb 15, 2026 · Transmission · MS

A couple times I heard loud clanking coming from rear brakes. One time in particular I was trying to stop and it felt line someone had ran into my truck but must have been the rear wheel locking up

Filed Oct 14, 2025 · Transmission · SC

Torque converter in my transmission we out, causing my gears to grind and lose power. Slight rumbling sound under the front passenger seat, First dealer (Palmen Motors, Kenosha WI) told me there was nothing wrong with the vehicle and no transmission error codes exist. Second dealer (Parks GMC, Greenville SC) indicated that i need a complete new transmission. Part is on backorder for the last 4 weeks and I am without my vehicle. No ETA for new part or any information on why it failed prematurely.

Filed Aug 11, 2025 · Transmission · 166,000 miles · SD

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.

Filed Jul 7, 2025 · Transmission · 125,000 miles · MA

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 the federal safety agency 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.

Filed Jun 24, 2025 · Transmission · CO

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, the federal safety agency 24V‑797. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? Mine has been rejected by GM. Although I documented and photographed the failure codes, I cleared them from the vehicle in order to attempt to safely get to the dealer and prevent further damages. Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? At the time of failure yes, check engine light and codes from an engine monitor coinciding with the known problems. Engine speed / power was reduced to allow only 5th gear.

Filed May 17, 2025 · Transmission · CA

After the transmission recall was completed, I’m now having erratic shifting. Having the recall adding software monitoring for a hardware issue is inadequate. Now that I am out of warrentee, gm has not resolved the issue and now I am having shifting problems.