2020 GMC Sierra 2500: check engine light

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 Jun 30, 2026 · Engine · 100,000 miles · LA

The contact owns a 2020 GMC Sierra 2500. The contact stated that the check engine warning light was illuminated, and the message "Reduced Power" was displayed. The vehicle was taken to the dealer, where the turbo actuator and wastegate position sensor A-circuit were replaced; however, the failure persisted. The vehicle was taken back to the dealer, and the contact was advised that another diagnostic test was needed. The contact declined to pay for the diagnostic test. The vehicle was taken to a retired GM mechanic, who diagnosed the vehicle with turbo charger failure. The vehicle was not repaired due to the cost. The manufacturer was notified of the failure, but no assistance was provided. The failure mileage was approximately 100,000.

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 Apr 18, 2025 · Engine, Fuel system · 125,000 miles · FL

The contact owns a 2020 GMC Sierra 2500. The contact stated that the vehicle was under the federal safety agency 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 transmission could not be diagnosed until the injector was repaired. The manufacturer was informed of the failure and opened a case. The failure mileage was 125,000.

Filed Jan 14, 2025 · Engine, Transmission · 114,000 miles · TX

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 the federal safety agency 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.

Filed Mar 14, 2023 · Engine · KY

Check engine came on Sunday morning the code that through was P0 526 u062F. After calling the dealer and setting maintenance to be done one day later, the truck broke down while driving on the side of the road. The dealer is saying that the belt came off and the tensioner locked up doing damage to the fan clutch and connector. The case, because the code that ran is saying that the belt wasn’t going the speed that it was supposed to because the tensioner failed. The vehicle only has 55,000 miles on it.

Filed Jan 23, 2022 · Brakes, Electrical · KS

Truck has had multiple issues related to the electrical system and truck modules. It is my opinion that these are all related to voltage issues or module problems. i have had multiple infotainment issues with delays loading, freezing up etc. dealer has ran updates and checks with nothing found. In October around $35k miles the truck Radio would not work if i used the push button start. if i shut the truck off opened the door and let everything reset i could push the start button in the truck and the radio would work majority of the time. The next day i went out to a completely dead truck. I talked to my service department at the local dealer and they said i would need to bring it in but suggested i disconnect the batteries and recharge the batteries. after doing so everything started working correctly. it fixed my radio problem and never went dead again. since then i have experienced popping noises through the speakers when playing music occasionally. over the last few weeks i noticed the engine does not attempt to increase cold idle speed until i press the brake to put it in gear. January 22nd i hit the autostart button and it did not work. i started the truck and it had CEL, Traction control, park brake and wrench, lights on with service emissions, and power reduced messages displayed. Truck is running odd. codes present are (ENGINE GMLAN)P0118 - engine coolant temp circuit high voltage, (BRAKES GMLAN_ABS) U0401- invalid data from engine control module, P0562- system voltage low, (HVAC CONTROLS GMLAN_HVAC) B1325 - . control module power circuit. Truck is starting and charging fine. No connection issues at batteries. There are many TSB's and many complaints regarding similar issues. common brake and emissions faults with minor differences. Module failures, communication faults, and or electrical faults are likely causing all of these similar issues. they need to be categorized as the same failure group which will show GM has a bigger issue.

Filed Oct 2, 2020 · Electrical, Engine · 212 miles · MI

As I was driving home my check engine light came on and all of my lights went out. I had no tail lights and the radio started saying no signal detected. The dash screen was saying service keyless entry system. And I had no running lights but my headlights. Pretty scary thinking no one could see me as they were driving behind me at a high rate of speed. My truck only has 200 miles on it so this is really scary to be having issues so early in the ownership of this truck. I've always had fords but this truck caught my eye and I stepped out of my comfort zone and now wishing I would have stayed in in.