2023 GMC SIERRA 2500 Power Train Problems

The contact owns a 2023 GMC Sierra 2500. The contact stated that while driving approximately 35 MPH, the vehicle went into LIMP Mode, and the message "Service Transmission" was displayed. The vehicle was taken to the dealer, where it was diagnosed that the transmission valve body rod had failed. The valve body rod was replaced. It was unknown whether the vehicle was repaired. The vehicle remained at the dealer. The manufacturer was not notified of the failure. The failure mileage was approximately 44,546.

Mileage: 44,546

Bought a 2023 gmc sierra 2500 duramax. Went into limp mode took it to dealership the transmission was bad so they replace transmission after 3 month of dealer having my truck . Got the truck back still having issues with transmission not shifting right and the rear tires locking up at highway speeds .

The transmission control mod is bad. This is a persistent problem and that's why it is on back order for up to a year. It is unethical to not issue a recall as customers have to continue to pay for the vehicle while not getting a replacement of equal capabilities. I bought a 3/4 ton truck to haul for work, not getting something that can do the same while a pay $1000+ a month is wrong. For the NHTSA not to get involved, issue some sort of recall, and allow GM to continue to take people's money while their vehicles depreciate is wrong. Is this so the government can get paid back from GM for the bailout 15 years ago?

This issue is pertaining to the valve body in my 10-speed transmission. While I was traveling home, the truck experienced a “wheel lockup”. The transmission shifted down aggressively, then putting the truck into limp mode. I had to travel the rest of the way home with a max speed of 35 mph. I have been without this truck for 3 months waiting on parts. This is absolutely unacceptable from gm. Extremely unsave.

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.

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.

I rely heavily on this vehicle for my business and within 1 year of ownership, the vehicle broke down on the highway allowing it to only run @ 30mph. After finally locating a dealer who could evaluate the vehicle in less than 1 week, I was informed that the part was unavailable and they indicated, "it could take 1 month or 3 months to receive." Following multiple conversations, I was forced to open a claim with GM Customer Care. While trying to get information, I was, at one point, told that "although the code indicates failed transmission control module, it doesn't happen all the time and if I wanted to drive it I could come and take it until the part arrives." That really told me alot about how GM representatives view SAFETY while when it happened, I was on Interstate and nearly got trounced by oncoming heavy traffic while pulling an equipment trailer. After the case was handed off to several GM Customer Care Representatives, I finally rec'd feedback including several email updates. I finally rec'd the vehicle back after 1 month and was informed that 1) would receive car payment from GM & 2) would receive additional compensation for lost work time while my vehicle was out of service (Jan 2024). Since that conversation, I did receive 1 car payment however, never heard back from Alisa regarding "lost time". I have sent several emails to customer care asking for an update however, crickets. Furthermore, the car has returned to the shop for another warning to "shift vehicle to park" when it was in park. They told me its a electrical malfunction but they could not get the error to come up on test. I have a photo showing the error.

The contact owns a 2023 GMC Sierra 2500. The contact stated while driving approximately 40 MPH, the vehicle shook abnormally twice and then switched to Low Power Mode. The contact stated there was no warning light illuminated. The contact had the vehicle towed to a local dealer, where it was diagnosed and determined that the transmission valve body needed to be replaced. The contact stated that the valve body had failed within one and a half year. The contact requested that the entire transmission be replaced. The manufacturer was informed of the failure and declined to replace the transmission. The vehicle was not repaired. The failure mileage was approximately 42,000.

Mileage: 42,000

Two times with my truck, the transmission has locked up solid while towing a heavy load almost causing my load to shift and wreck my truck in traffic. It happened at 60k miles and again at 68k miles. The truck shutters and then locks up solid on the transmission, then after a second of sliding, it releases and goes into limp mode. This is a serious issue when it is uncontrollable. It felt like my trailer had broken loose and slammed into the cab when it happened. I'm sure it wasn't good on the truck in general. A code scanner read P0747 code and it appears that GMCs recall does not cover my truck in another recall for the same issue with 20-22 model trucks. It is happening all the way up to the 25 year models from what I read.

Shift to park message displayed while attempting to shut off engine after shifter was in the park position, accessory would not turn off even after driver door opened and could not leave vehicle.

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.

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.

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.

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.

The valve body inside the transmission has failed and GM has known it to fail but they have done nothing about it. My vehicle has been in the shop for 2 months because of it and “parts are on back order” it’s terrible i’ve bought this vehicle in august and it’s constantly been inside the shop for various issues. My transmission lost 7th gear and it came to an immediate stop in the road because of it. tires screeching and all. truly embarrassing that you can spend 83,000$ on a truck and it be such a peice of junk.

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.

Mileage: 25,000

The contact owns a 2023 GMC Sierra 2500. The contact stated that while driving at an undisclosed speed, the contact smelled an abnormal odor. The vehicle was taken to the dealer; however, no failure was found. The contact stated that while driving at an undisclosed speed, the contact heard an abnormal sound and smelled an abnormal odor. The vehicle was taken back to the dealer, who diagnosed the vehicle with an oil leak; however, the dealer was unable to determine the location of the leak. The manufacturer was not made aware of the failure. The failure mileage was approximately 6,000.

Mileage: 6,000