Engine goes to limp mode multiple times 3 of which happened getting onto the highway and almost creating an accident due to the reduced acceleration mode. CODe u0656 00 popped up each time. Dealer has yet to rectify due to lack of appointments-?? making me keep the vehicle saying it-??s drivable but each time randomly goes into the reduced acceleration mode every restart. (Blasius GMC Branford CT)

- Brandford, CT, USA

In late February/early March, my GMC Sierra with around 9000 miles had the following to occur on a cold start: check engine light came on as well as the service esc light & traction control light, truck shuddered and shimmied. Took for service on March 4, 2024 with 9774 miles on odometer, where service tech said they couldn't duplicate concern (see attachments: March Service Invoice Pg 1 & 2). Took truck home & same issues kept occurring especially on cold mornings & days. Took the truck back for service on April 1, 2024 with 10895 miles on odometer. Told them to keep it till its fixed & to start it on cold mornings because thats when problem occurs. They had truck till April 12, 2024 and were able to duplicate the concern. Dealer changed the fuel injector (that was not the problem). Service tech finally found the cylinder 8 has a misfire until vehicle gets to operating temperature. They replaced all 8 lifters in bank 2 (right side) & gave me an oil change. This seems to have fixed the problem, but I won't really know until winter 2025. My problem with this lifter issue is that this engine will probably only last for 3 maybe 4 years tops because of all the metal shavings that are roaming around in the engine. This has been a problem with GM engines for some time & GM has yet to fix it or at least take responsibility for their poor engineering. I paid over $70,000 (of which GM made around $17,000) for this truck only to have the engine probably make it for a few years. My last truck I kept for 10 years. I don't see this happening with this truck.

- Summersville, WV, USA

The transmission failed as I as was turning on to a highway. It seemed like it was rapidly shifting between two gears, but I could not accelerate for several seconds and had to immediately pull over into the ditch to avoid a high speed collision. I took it to the shop the next day. The transmission valve body failed, which appears to be a common issue as I've researched incidents like this online. The part was on backorder. Once it arrived at the dealership, the replacement valve body immediately failed again. Now a 3rd valve body is on backorder with no ETA. I've been without my truck for over a month now with no end in site, and I do not have confidence that a 3rd replacement is going to provide a proper and long lasting fix.

- Van Alstyne, TX, USA

The contact owns a 2023 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the vehicle started to shake abnormally with the check engine warning light illuminated. The contact stated that after arriving at a parking structure, the transmission warning light illuminated. The vehicle was towed to the local dealer where it was diagnosed with transmission failure. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 15,000.

- Los Angeles, CA, USA

The contact owns a 2023 GMC Sierra 1500. The contact stated that the vehicle was idling excessively high without the accelerator pedal being depressed. While driving 70 MPH, the tailgate unintendedly opened. The tailgate warning light was illuminated. Additionally, the blind spot detection warning light illuminated without another vehicle being nearby. The vehicle was taken to the local dealer, who was unable to duplicate the failure. The vehicle was not diagnosed or repaired. The manufacturer was not contacted. The failure mileage was approximately 6,100.

- Wichita, KS, USA

Truck has died going down the road at 40mph. Also have electrical issues with radio..running boards opening going down the road. No sound from radio, signals...no connections to google on star lost. Radio screen half of screen shuts off. Front crash sensors go off with noting in front of vehicle...loss of cameras no connection. Sounds like a bug zapper under truck. GM has reprogrammed truck now 3 times sent a tech from factory...replaced radio reprogrammed all computers again!! truck has been in the shop this time for over 30 days with 6200 miles on it this is the 4th time since I bought in June. Have a case representative from GM who will not help with issues just keeps putting me off. Have videos pictures of all the issues and have given to dealer and

- Pekin, IL, USA

The contact owns a 2023 GMC Sierra 1500. The contact stated while driving approximately 60 MPH, the vehicle inadvertently decelerated to approximately 30 MPH and went into LIMP Mode. The check engine warning light, the service power steering warning light, the service transmission warning light, the low tire pressure warning light, and the traction control warning light were illuminated. The contact stated that a message was displayed on the instrument panel to -??Service 4-WD and -??Reduce Acceleration - Drive with Care. The contact stated that the climate control system increased to 76 degrees. The vehicle was taken to the dealer where it produced codes: P00FF, P1789, P25A2, U0073, U0402, U0418, U1610, U1643; however, the failure could not be duplicated. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 5,000.

- South Salem, NY, USA

At just 600 miles, the 2023 GMC Sierra 3.0 Duramax gave out a check engine light. The code reader displayed a P0402. The truck had a very strong fume odor. The truck was taken to service two times. GM engineering made tests on the truck and concluded that the truck needs to be reprogrammed. I have a case number established with GM (case number 9-9217617941). If the program is bad, why release the product to the public? See attached invoice for details. This issue is present on almost all LZ0 GMC trucks based on people I've met in forums. Please help us.

- El Paso, TX, USA