GMC Sierra 2500 check engine light comes on

Filed Oct 27, 2026 · Transmission · GA

At approximately 84226 miles, the subject 2022 GMC Sierra 2500HD AT4 experienced a transmission cooler line failure. The owner’s preliminary observation is that an adjacent oil line contacted and abraded the transmission cooler line, ultimately producing a through-wall opening. Driver (Owners Son) experienced perceived issues with shifting on his drive home including surging RPM. By the time he arrived home he had concerns about it not shifting gears properly. The next day the owner noticed vehicle fluids on the concrete driveway under the vehicle. Vehicle would not engage in forward or reverse gears. Owner observed a burnt smell in the trucks’ cabin. No check engine light or similar errors were observed. Further inspection showed evidence of fluid on exhaust components.

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 · Electrical, Engine · CA

The vehicle experienced a loss of engine power accompanied by a check engine warning light and a “Reduced Acceleration”/reduced-power condition. The exact component causing the malfunction has not yet been determined. The vehicle and any affected components are available for inspection upon request. While driving the truck uphill toward our residence, the vehicle lost significant power and had difficulty maintaining acceleration. The truck stalled several times. The sudden loss of engine power while driving on an incline created a safety risk because the vehicle was unable to maintain normal acceleration and could potentially have stopped in traffic or created a hazard for other vehicles. The problem has not yet been confirmed or reproduced by a dealer or independent service center. The vehicle has experienced the problem while being driven, including the reduced-acceleration condition and multiple stalls. The vehicle will be inspected by a GMC dealer on Monday, September 28, 2026. The check-engine warning light illuminated, and the vehicle displayed a reduced-acceleration/reduced-power condition. The truck subsequently experienced significant loss of power while traveling uphill and stalled several times. These symptoms first appeared on September 14, 15, 22, and 23, 2026.

Filed Sep 16, 2026 · Electrical, Engine · ME

driving down the road going to and intersection the dash says I received a Service ESC message followed by a Reduced Acceleration warning on the center display. I also had the forward collision, traction control and check engine lights come on. I also noticed the shudder/jerk. The truck is giving a P060C code and when i was driving it dies in the intersection of the road and will not start back up. puts the computer in a safety mode. I have call my local GM dealer and they did not fix it and it happen twice. I the truck dies in the middle of the road and no way to start's it and if a big rig crashes in to the truck some one or more than one will be hurt or killed

Filed Sep 3, 2026 · Acceleration, Transmission · NY

While driving my truck on the highway at 65 mph the truck bucked hard and immediately downshifted into 2nd gear. This caused me to rapidly decelerate to approximately 40 mph, I am lucky there was not another vehicle behind me when this happened since rapid unexpected deceleration without brake lights is very dangerous. I had to drive the truck in limp mode at 45mph and approximately 4500 rpms to the nearest exit. This event illuminated the trucks check engine light and displayed a brief service 4WD message followed by a permanent reduced acceleration message on the dash.

Filed Jul 7, 2026 · Brakes, Electrical · AK

On XXX, I was towing my camper to Copper Center, Alaska from Palmer, Alaska when my truck experienced a full transmission shut down which put the truck into "Reduced Power Mode". We descending down the road right next to Victory Bible Camp (64741 Victory Rd, Sutton-Alpine, Ak 99674) when the exhaust break turned off and the truck decreased power and the Check Engine Light illuminated. The Diagnostic that was produced by OnStar revealed 3 different codes. ( P0700 TCM, P0747 Pressure Control Solenoid A is stuck in the "ON" position, C116b faulty brake pad wear sensor.) I called GMC of Palmer and GMC OnStar advisor, both informed me that the truck needed to be towed. My safety concerns is this.... I had minimum cell phone signal and not a gas station or service station within MILES. I was on the side of the Alaska Highway 1 which is a major thoroughfare for traffic going to and from [XXX]. Thankfully there were a few kind folks that pulled over to offer assistance. My truck is a 2023 GMC Sierra 2500hd with only 26,262 Miles on it. I purchased this vehicle XXX. (It Still has the Temporary Tags on it.) If had been in a different part of Alaska when this transmission failed to function properly then we could be talking about a life or death situation. Especially, if my child was with me. I was hauling my camper that weighed ATMOST, 7,000 pounds. This is less than 40% of the trucks ability. I feel that this could put someone into a dire situation had they not had the experience with emergency situations like I have had. (Prior Military Service). I have also filed a complaint with GMC Motors. Case# XXX. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

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 7, 2026 · Transmission · OH

I was merging onto the highway in my 2024 GMC Sierra 2500HD AT4X equipped with the 6.6L Duramax engine at about 50mph when the gauge cluster emitted a “Reduced Acceleration Drive With Care” message followed by a check engine light. The check engine light presented indicated a “P0747” and “P0700” code. The vehicle was then stuck in 5th gear at highway speeds. Luckily there was no traffic present during this event due to the reduced acceleration of the vehicle and confusion caused to the operator. This could have been a dangerous situation due to the sudden change in handling of the vehicle. I have since then had the vehicle towed to the dealership in which it was purchased from for them to do their investigation to see how to fix the issue. This is a very well known issue with these GM heavy duty pickups. There is currently a recall on these trucks for this exact issue but my truck at this point in time is not included in said recall. I believe the recall is for 2020-2022 vehicles. Mine happens to be a 2024 which uses the same transmission as the older model vehicles in the recall. There are many other owners of these trucks like myself who have experienced this exact same issue. I’m sure this isn’t the first time this issue has been reported either. Something must be done about this.

Filed Apr 10, 2026 · Driver assistance, Electrical · 8,000 miles · IA

The contact owns a 2024 GMC Sierra 2500. The contact stated while reversing, the rear-view camera displayed a blank screen. The 4WD system engaged unintendedly, and the park assist sensor was inoperable while an unknown message was displayed. Additionally, the vehicle lost motive power while driving. The check engine warning light was illuminated. The vehicle was towed to the dealer, who replaced an unknown module and reset the computer, but the failure persisted. The contact stated that the vehicle was taken to the dealer five times, but the failure recurred after several unknown repairs. The vehicle was not repaired. The contact had requested for a buyback from the dealer, but no assistance was provided. The manufacturer was made aware of the failure. The failure mileage was approximately 8,000.

Filed Mar 3, 2026 · Engine · 63,800 miles · ID

The contact owns a 2017 GMC Sierra 2500 Denali. The contact stated that while driving at an undisclosed speed, the check engine warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed with a failure of the #8 glow plug. The contact was informed that all eight glow plugs were replaced. The vehicle was repaired. The contact stated that the failure was a known failure with the vehicle. The manufacturer was made aware of the failure, and a case was filed. The failure mileage was approximately 63,800.