GMC Complaints

Had a P1098 code. The truck was diagnosed by a certified technician. Found to have a failing coolant control valve. GM has issued special coverage for this known failure. Special coverage is not including the VIN for this truck although it falls in the criteria for model, year, and engine model.

The contact owns a 2022 GMC Sierra 2500. The contact stated that the engine was making an abnormal rattling sound on cold starts. There was no warning light illuminated. The vehicle was taken to the dealer, where the front muffler exhaust baffle was replaced; however, the failure persisted. The vehicle was taken back to the dealer, where the contact was informed that the rattling sound could not be heard; however, the contact stated that the rattling sound had become louder, and other individuals were able to hear the rattling sound. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was unknown.

I own a 2024 GMC Sierra Denali Ultimate 2500HD diesel that has been out of service for 52 days due to an oil cooler / service bulletin related failure. The vehicle is under warranty. The required replacement part is on national backorder and, as of today, has not shipped. The current estimated ship date is February 17. During this time, neither the dealership nor GMC has provided proactive communication. I have had to repeatedly contact them for updates. This extended inability to repair a critical component, combined with the lack of parts availability and communication, raises concerns about the reliability of this system and the manufacturer’s ability to support safe operation of the vehicle in a reasonable timeframe. The truck is my primary vehicle and is intended for towing and transportation. Being unable to repair it for nearly two months due to parts unavailability presents a significant safety and reliability concern.

2025 GMC Sierra 1500 has had 2 engine failures since purchase date June 2025. Engine failed on a road trip with my family, leaving me stranded for hours. After the problem being resolved, engine failed once again after 5 months. On the dash it said loss of power and wouldn’t crank to turn ON

My 2026 GMC AT4 3.0L Duramax had a catastrophic engine failure on Sunday, February 8, 2026. It went into reduced acceleration and also fault code PO6DD. Thankfully I was not on a highway. The truck would not run over 45 MPH on flat ground, and then by the time I got it to a safe location 5 miles away it would not run over about 30MPH. This obviously resulted in the truck being towed to a dealership. I have been told the entire engine will be replaced. Upon further reading, I suspect this is a thrust bearing failure that is a well-known issue in this LZ0 Duramax engine. What I have read, this issue is occurring mostly on trucks built from May-Sept 2025, and my truck has a 7/2025 build date. This could have been major safety hazard if the engine had failed in a major freeway/highway.

Rear heater line leak detected during evaluation of engine code P01F0 and empty expansion tank was noted. There was never any puddle in my garage prior to the incident, and nothing detected after the fact either. Pictures included demonstrate a leak at the double-crimp near the farthest rear point of the vehicle. The other hose behind the drip photo was also leaking at the crimp under the secondary piece of hose insulation. The design of the system requires replacement of the entire heater line assembly (4 pipes, associated hoses and fittings) traversing the entire length of the vehicle. I was told this is a dealer-only part.

Failed component was thermostat and I do not have possession of it. Over several months, I would receive infrequent and unrepeatable messages of "steering assist reduced" and my temp gauge would drop all the way to the cold side. No other recorded codes were being set after frequent trips to Autozone for verification and there were no check engine light warnings. No other signs of vehicle malfunctioning were present either. Recently, a code was finally set P01F0, so I had something tangible to take into shop as the prior condition was not repeatable. Hoping it was only the coolant temperature sensor, then ultimately learned the thermostat had failed - the much more expensive repair option. Seeing this complaint relatively frequently with the 3.6L engine on NHTSA. Plus, the tech says he has changed at least 100 of these - Acadias, Traverses, Enclaves, etc., any GM product with this engine and poor design/position for the thermostat.

Post initial remedy, which included oil sand cap replacement to 0-40, as directed by the manufacturer's recall documents, and passing the PicoScope test on August 26, 2025, the vehicle lost propulsion while traveling 58 mph, in the center lane of a busy, notoriously dangerous Saeford-Oyster Bay highway. At the time, the vehicle was occupied by a 2-week-old infant, the child's mother, and a dog. Prior to the failure, there were no indications of a pending or present issue. The vehicle's engine shut off, it shifted into neutral, and upon stopping, it shifted into a parked position, where it remains to date. Subsequent to pulling the vehicle onto the shoulder, the engine failed to restart. Approximately 6 hours later, the vehicle was towed to a GMC dealer, which subsequently confirmed that the engine is seized. The dealer submitted a report to GM to remedy the condition, pursuant to the manufacturer's recall instructions, but the manufacturer is yet to approve the remedy.

The contact owns a 2022 GMC Canyon. The contact stated that after starting the vehicle, the instrument cluster failed operate as designed and the speedometer, tachometer, fuel gauge, and turn signals failed to display as intended. The contact stated that a message to service several systems was displayed. The radio screen was blank, and the back over prevention system was inoperable. The vehicle was taken to the local dealer to be diagnosed, and it was determined that several software updates were needed; however, it was then determined that all the software was up to date. A software refresh was performed, and the vehicle was repaired. The manufacturer was notified of the failure. The failure mileage was 39,500

The contact owns a 2019 GMC Sierra 1500. The contact stated that the vehicle made an abnormal rattling sound while idling. Additionally, while driving at 45 MPH, the message "Reduced Power" was displayed, the check engine warning light illuminated, and the vehicle stalled. The contact was able to coast to the shoulder of the roadway. The vehicle failed to restart and was towed to the dealer, where it was diagnosed and determined that there was no compression in the engine. The dealer determined that the engine needed to be replaced. The dealer advised the contact that the repair was not covered because the VIN was not under recall. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was approximately 126,000.