GMC Complaints

Transmission started slipping a little and then literally stopped working all with in an hour. And was doa in the parking lot.

On the afternoon of 01/20/26, I was merging onto the highway in my 2021 GMC Sierra 1500 when a loud bang was heard from the engine compartment at approximately 60 mph. Immediately after the ban was heard, several indicator lights on the dashboard were illuminated, including the ESC, check engine light, and parking brake light. A power loss was felt when attempting to accelerate and the banging noise worsened anytime the accelerator was depressed. I was able to drive the vehicle to the nearest GM dealership that coincidentally was at the closest exit off of the highway I was traveling on. The dealership performed diagnostic and determined that the damage was caused due to the ongoing GM recall associated with Safety Recall N252494000. My vehicle had previously been inspected as part of the recall and was found to have passed. Vehicle had been driven approximately 4,000 miles after recall was performed.

The engine seized up traveling about 40MPH in the middle lane on a busy road with my child in the passenger seat. I was able to get off the busy road but part of my truck was still intruding into the lane. The truck is parked at my house. The vehicle has not been inspected by anyone and is still in the same condition as the day the engine seized. The only thing that indicted any issue was a couple popping noises right before the engine seized. It all happened while I was driving in traffic and I did not notice any indications on dash. I was more concerned about getting off the road and out of traffic before I got rear-ended or involved in a pile up.

I have been dealing with a sweet/Christmas-like smell in my car occasionally for the last several months. This is a health & safety concern for me involving ethylene glycol fumes in the cabin. These fumes could be linked to why I have experienced increased sinus headaches over the past several month. I took it into CarMax (where I purchased the vehicle) and they were able to diagnose the issue and state that my heater core needed to be replaced. However, since my vehicle was under 36,000 miles, it needed to go to the dealer. The dealer that has been working on the vehicle is Hendrick Hoover Chevrolet. I have taken the vehicle to the dealer twice already and they have not been able to diagnose it the same as CarMax nor recreate the smell. Both times I have picked up the vehicle, I smelled the same thing within 1 day of having the vehicle back. Today (1/22/26) I took the vehicle back to CarMax to have them take it to the dealer for the THIRD because I have not only smelled the same smell, I have 2 new issues that need to be addressed. They are not the reason for this complaint, however. But for documentation purposes, it involves servicing the safety restraint system and error codes P0018 and P0021. I do not have any records of the first time I took the vehicle to CarMax/Dealer in November of 2025, but I have attached the records from the latest visit where I dropped the vehicle off on 12/10/25 and picked it up on 1/14/26.

IntelliBeam will sometimes allow me to activate the system but will turn itself off and not allow it to be reactivated until the power is cycled. Other times it will not activate at all. This is on a dark backroad with no traffic.

around chirstmas, Was driving on the highway and the car threw a "reduced engine power" warning and went into limp mode. Check engine light came on. Car asymptomatic prior. got the code pulled and it said turbocharger under boost. The next day the check engine light went out and car was running appropriately. Took the car on the highway again and the car threw the "reduced engine power" warning and went into limp mode again in the middle of freeway traffic. It is a safety concern due to the engine going into limp mode in the middle of high speed traffic. I easily couldve caused an accident putting both myself and others in danger by the engine cutting the power in the middle of the freeway. The check engine light only comes on while going at freeway speeds. The light will then go out overnight and come back on the next time i go back on the freeway at 70-80mph speeds. I have taken it to one shop which reported an oil leak coming from the turbo both inside and outside and that it needed to be replaced. I have read several different forums of other users of the same year, make, and model experiencing the same issue. the car is only a few years old and the likelihood of a turbocharger being bad is uncommon but a major safety concern considering this happened out of nowhere with no signs or symptoms leading up to this.

Been happening for a year and a half. Muffler is very loud and rattles constantly. Getting worse over time. There is a current recall but my vin isn’t included even though my car is having the same issue.

I am filing this complaint to report a catastrophic engine failure involving my 2017 GMC Terrain equipped with the 2.4L Ecotec engine, which I believe is the result of a known manufacturing defect related to excessive oil consumption and premature internal engine wear. At approximately 88,000 miles, my vehicle experienced severe engine failure, including excessive oil consumption, timing chain failure, and complete engine failure, which has been confirmed in writing by a licensed repair facility. The shop determined that the engine failure was caused by oil starvation resulting from excessive oil consumption, leading to internal engine damage and timing chain failure. This failure occurred without warning and rendered the vehicle unsafe to operate. Sudden engine failure creates a serious safety risk, including loss of power while driving, inability to accelerate, and increased risk of collision. This engine failure matches a well-documented defect pattern involving General Motors’ 2.4L Ecotec engines, which have been the subject of class-action lawsuits, settlements, and jury verdicts related to premature piston ring wear, excessive oil consumption, and resulting engine damage or failure. These issues have been widely reported in Chevrolet Equinox and GMC Terrain vehicles within my model year range. My vehicle was properly maintained, and this failure was not the result of neglect, misuse, or normal wear and tear, but rather a latent manufacturing defect that manifested after the warranty period but well within the reasonable life expectancy of the engine. I am requesting that NHTSA formally document and investigate this defect, as it presents a significant safety concern for drivers operating vehicles equipped with this engine. I also request that General Motors be required to address this defect to prevent additional engine failures and potential safety incidents.

The contact owns a 2021 GMC Acadia. The contact stated that while the vehicle was parked, the vehicle started, and the contact exited the vehicle and ran into the house for a while. The contact stated that while reentering the vehicle, the contact noticed that the check engine warning light was illuminated. The contact was employed by an independent mechanic, and the vehicle was driven to the place of employment. The independent mechanic attached the mobile diagnostic tester to the vehicle and retrieved DTC: P023F, which indicated fuel pump secondary circuit failure. The contact was advised that the fuel pump module needed to be replaced. The vehicle was not repaired. The vehicle was not repaired. The contact referenced NHTSA Campaign Number: 21V422000 (Fuel System, Gasoline); however, the VIN was not associated. The manufacturer was made aware of the failure but provided no assistance. The contact was advised to contact the NHTSA Hotline to report the failure. The failure mileage was approximately 78,200.

This has happened twice. Once in November 2025 and then in January 2026. With super cruise engaged while going around a curve super cruse disengages and the steering wheel turns to driving straight. You have about one or two seconds to take control or crash. This happened while driving about 70 mph on interstate I 70 and next on Ohio 122 going about 45 mph. On I 70 it was a gentle curve and on 122 it was a much sharper curve. Super cruse must give a warning that it about to disengage that is much longer than one or two seconds.