2023 GMC Sierra 2500: check engine light

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 Jul 9, 2025 · Transmission · GA

While driving the vehicle, I entered onto the interstate, as I accelerated into the flow of traffic, (approximately 45-50 mph) my truck suddenly and unexpectedly jerked and “clunked” extremely hard, I thought I had ran over a large object, approximately 5 seconds later it jerked and “popped” loudly. At that time the reduced engine power and check engine light came on causing my vehicle to suddenly slow down to 20 mph and almost being rear ended by a tractor trailer truck traveling the speed limit that had to hit his brakes e trebly hard to avoid a rear end collision. After removing my truck from the flow of traffic, I turned it off, exited the vehicle to see if I had ran over something, I did not. Cranked it up, no signs on the dash, as I started back to the travel lanes, it “surged & jerked” the reduced power and check engine light came back on. Once I got the truck to the dealership, the service manager informed me he knew exactly what it was, the transmission valve body was no longer good. He also informed me that my truck was now number 28 in line just at that dealership for the same issue and repair, then added that GM is out of stock on the parts and back order status.

Filed Jun 27, 2025 · Transmission · IN

The contact owns a 2023 GMC Sierra 2500. The contact stated while driving 35 MPH, the vehicle gear shift was shifting independently, and the contact noticed the vehicle was shaking and the vehicle went into limp mode. The check engine lights illuminated. The contact pulled over to the right side of the road turned the vehicle off and then turned the vehicle back on and the failure persisted. The contact the gear shift was stuck in fifth gear. A dealer was contacted. The vehicle was taken to the dealer where it was diagnosed that the valve body needed to be replaced. The vehicle was not repaired. The manufacturer was notified on the failure and opened a case. The contact was referred by the manufacture to report the failure The approximate failure mileage was 50,823.

Filed Mar 14, 2025 · Transmission · OH

2023 GMC Sierra 2500 AT4 with approximately 36,000 miles as of current. The vehicle has experienced three valve body failures to date. GMC dealerships have completed one GM remanufactured transmission replacement and an overhaul of the second transmission. The third valve body has now failed. A GMC transmission specialist confirmed transmission failure upon recent test drive on 2/24/2025. GMC dealership refuses to perform warranty repair as they are stating “a recall is being developed” therefore will not repair/replace current defective powertrain parts. I was given the vehicle back with the verbal disclaimer “it should be safe to drive but the rear wheels can lock up at highway speed so be aware.” The failure causes extreme harsh downshifting and what feels like a momentary rear wheel lock up. I have experienced this numerous times at lower speeds (<40mph). The check engine light does not come on.

Filed Feb 27, 2025 · Transmission · AZ

As I was driving on a paved public road, my truck shifted up/down multiple times on it's own in quick succession, then jerked the truck forward. The check engine light came on and the driver information center displayed 'Engine power reduced'. I had to return to my home which was closer than a dealer for service. I'm fortunate that this didn't happen while towing as I regularly do or while I'm on the freeway which I use several times a week. There was no warning that this was going to happen (e.g., no indicator lights or messages or even strange behavior from the vehicle). The GMC dealer confirmed the valve body in the transmission needs to be replaced and the part is on backorder with no ETA.

Filed Nov 14, 2024 · Engine, Transmission · IL · 1 injury

I was driving on the interstate and had just exited to refuel. As I was re-entering traffic, I accelerated to merge, and suddenly, as I was about to pull in, I felt and heard a massive metallic crash, like the entire transmission had dropped. The engine sounded abnormal, and immediately, the dashboard flashed a warning: 'Engine Power is Reduced.' The check engine light came on, and I got messages saying the transmission needed service and to schedule an appointment. I called my dealership and took it in as soon as possible. After they held the truck for a while, the service manager told me a critical part was on indefinite backorder with no fulfillment date. He handed back my keys, saying they'd reach out when it arrived. I asked if it was safe to drive, and he said yes. Later, driving from Illinois to California, my truck malfunctioned again. This time, in heavy, 12-lane traffic, the same loud crash threw me forward, almost slamming my face into the steering wheel. My wrists and shoulders hurt from bracing myself, and my right shoulder still aches. Again, I got the 'Engine Power Reduced' warning and transmission service notice. Each time, this has put me and those around me in severe danger.

Filed Oct 8, 2024 · Engine · CO

Defective valve body We took in our vehicle for issues with the engine. We were not able to drive it over 50 mph it only has 22,000 miles. The dealership has had the vehicle since August 13th. They have had the vehicle for 9 weeks. They said that neither them or customer [XXX] (CASE # [XXX]). Can locate a valve body, to replace the defective one. We were made aware that we had an issue when our check engine light came on. We proceeded to have a diagnostic done thru on-star. Then immediately took it to the dealership for repair. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Sep 9, 2024 · Transmission · MI

2023 GMC Sierra Duramax Diesel with 10 speed Allison Transmission with 28,000 miles can't be driven. Currently at the dealership due to a transmission valve body problem, codes P0700 & P0747. While driving I felt a hard shift and the truck jerk. The engine light came on and my truck went into low power mode. Let it sit over night and truck would shift fine. This happened 3 times over a 1 month period. After getting to the Chevy dealer they told me the issue is with he valve body and said they have been having multiple trucks come in with the same problem. They have a truck in there since May (4 months!) They told me there is no ETA for the part. I've read this is a common issue happening on 2023 & 2024 trucks like mine. I've read that the problems have been going on for over 1 year. This is ridiculous for a $90,000.00 truck. GM should be putting new transmissions in them or buying the trucks back. I'm considering contacting an attorney to inquire about the lemon law or what other avenues I can take regarding getting the truck fixed, and fixed properly.

Filed Apr 11, 2024 · Transmission · 25,000 miles · VA

The contact owns a 2023 GMC Sierra 2500. The contact stated while driving 45 MPH, the vehicle was losing motive power. The contact depressed the accelerator pedal; however, the vehicle failed to respond. The contact stated that the engine was revving abnormally. The contact stated that the check engine and an unknown "orange-colored" warning light illuminated. The contact pulled over and turned the vehicle off and was afraid to restart the vehicle. The contact had the vehicle towed to a local dealer where it was diagnosed and determined that a valve in the transmission needed to be replaced. The vehicle was not repaired. The manufacturer was not informed of the failure. The failure mileage was approximately 25,000.