GMC Complaints

With no warning signs, vehicle abruptly stalled while driving. I attempted to restart multiple times. Finally restarted and drove another 100ft and stalled again now with a check engine light. Made it to local shop and code P129F was found for fuel pump module. I see there is a recall on this but not for my particular vin. Recommend expanding recalls.

Driving on the highway when the steering warning light came on and then I had a loss of complete steering on the highway. Somehow was able to get off the highway but not completely off the road. Back end of the vehicle was still in harms way I could not turn that wheel at all this is a complete safety issue and could have easily caused an accident and could have been deadly. There was no warning before that just went out while driving at highway speeds on the highway. Also had to wait two hours for a tow. Vehicle is currently being diagnosed at the dealer and will provide all receipts once completed. This is an issue that needs to be addressed. Huge safety concen

The failure involved the engine (6.2L L87 V8), specifically suspected internal components such as the crankshaft and/or connecting rods, as identified in a current recall. The vehicle is currently located at Dennis GM in Corner Brook, Newfoundland and is available for inspection. On March 9, while driving the vehicle normally on a main highway, the engine suddenly lost all power without warning. The accelerator became completely unresponsive and the vehicle rolled to a stop in the middle of a main highway. The engine would not restart. Due to the electronic gear selector, the vehicle could not be shifted into neutral, leaving both the truck and trailer immobilized in a live traffic lane. This created a serious safety risk to myself and other motorists, especially as I was in an area without cellular service and could not immediately call for assistance. The problem has not yet been formally diagnosed, as the vehicle remains at the dealership awaiting inspection. However, the symptoms are consistent with known failures described in the recall affecting these engines. The vehicle had previously undergone recall inspection on September 1, 2025 and was cleared at that time. The vehicle has been inspected previously by an authorized GM dealer as part of the recall process, but no defect was identified. It has since been towed to Dennis GM following the failure and is pending further inspection. No police or insurance inspections have been conducted. There were no warning lights, messages, or prior symptoms before the failure. The engine failure was sudden and without any indication of an issue beforehand.

The vehicle experiences a transmission/drivetrain defect involving delayed gear engagement, hesitation, and apparent slipping. When accelerating from a complete stop (especially onto an incline) the engine RPM increases but the vehicle fails to accelerate as expected. The vehicle jerks and shakes violently and is unable to gain speed. This issue is intermittent but highly repeatable and occurs almost every time when there is a slope immediately after a stop sign. It results in loss of acceleration, violent shaking, and inability to maintain or build speed, creating a serious safety risk in traffic. It first happened around 1 year (early 2026) after the new car purchase (Nov 2025). There are no warning lights or messages. The dealer claimed they were unable to reproduce the issue during a brief test drive without me present and incorrectly attributed it to a bulletin without performing a detailed diagnosis or repair or looking at the video we recorded on the issue. The issue persists and affects safe operation of the vehicle. No inspection has been done by police or insurance. In one instance, this occurred while other vehicles were approaching from behind, creating a dangerous situation where I could not accelerate to match traffic flow. This resulted in a high risk of being rear-ended due to the unexpected loss of acceleration. I am aware of other consumer reports describing similar transmission-related symptoms such as slipping, hard shifting, and hesitation in this model. Some complaints describe transmission issues occurring at low mileage without warning lights.

Engine failed, no check engine lights turned on. Needed to have the truck towed to a dealer

To the best of my knowledge… My 2020 GMC Sierra Denali with a 6.2L engine and 74,000 miles had a complete engine replacement. One lifter on bank 2 was stuck, and the push rod in the cylinder was bent. The engine made a popping noise when starting. I took it to a GM dealership, where they quoted $9,200 to repair the issue or $9,600 for a brand-new engine with a 3-year/100,000-mile warranty. I know there is open recalls for 21’-24’ Models, but I would like some help with mine. This kind of problem shouldn’t happen on a GMC - loaded truck with only 74,000 miles. Thank you!

Automatic brake engaged unnecessarily/ unexpectedly while driving forward at a low speed. There was no reason for the brake to engage. There were no objects or people infont of us. This has happened twice in less than a month. Both times we were in a forward motion. It could have been a serious situation if the car behind us had been any closer when we suddenly breaked for no reason.

In November 2022, I started getting a dashboard "shift to park" on my 2019 Acadia after I had parked and shut the vehicle off. At the time I took it into service to have it looked at/repaired, they told me there would probably be a recall on this issue,as it seemed to be a frequent problem, and I would get a refund for the repair. That recall never happened, and now my car is once again displaying the same issue. The dealership will not cover the repair, and I will be responsible, as it is out of their 2 year warranty window. I can't just ignore this issue and keep driving, as with the "shift to park" display, there is a constant alarm that doesn't stop unless the park switch recognizes the car is in park, even when it is shut off. I feel this issue needs to be placed under a recall, and I should not have to pay AGAIN for it to be repaired.

Lifters broke and destroyed the camshaft at 99,000 miles. Total repair cost $8,200.

The engine (6.2L L87 V8) failed at approximately 85,000 miles. The failure was diagnosed as internal engine damage and the engine assembly was replaced. The failed engine is available to the manufacturer through the dealer as part of the repair process. The failure resulted in a complete loss of propulsion at highway speeds on the interstate, requiring immediate deceleration and maneuvering to a safe location, which created a safety risk to occupants and surrounding traffic. The condition was confirmed by a GM dealer using diagnostic procedures, including a Pico scope test, which verified internal engine failure. The engine was replaced under GM safety recall / special coverage related to L87 engine failure. The vehicle was inspected and repaired by an authorized GM dealership as part of the recall remedy. Prior to failure, there were no warning lights or messages. The only symptom was increasing engine noise and knocking from the lower end shortly before the loss of power. Failure occurred during normal driving conditions with proper maintenance. No crash, fire, or injury occurred.