GMC Terrain Problems — All Years, Common Issues & Reliability

Hard as rock brakes Long response time Mechanic friend says it’s break booster.

While driving the vehicle, the engine light came on, plus message board said service transmission and the engine went into limp mode. We let the car sit for awhile and checked the car. A scan said it was the pressure solenoid A in the transmission. The car sat for a day and the light was off. Drove the car and then it acted up again and now reverse doesn't work.

I bought this car new from Davidson's in Rome, NY in early March 2026. This is a 2026 model. Two days after I took possession, I noticed that the spare tire well was halfway full of solid ice. The car has a severe leak through the back right side window. The dealer states it needs to be replaced. The interior frames of the car were loaded with water for many weeks as it stood on the lot. Had the dealer done a final inspection of this car prior to transferring ownership to me, as they should have and stated they did, they would have found the solid ice that surrounded the spare tire and investigated the leak and repaired it BUT they would have been required to tell me of this leak I assume...if so, I would never have bought this car. They had the car in the shop now for 3 weeks as of today, April 20th, 2026, and no word on the resolution. They did give me a loaner car for use. They have to dry the car out completely and dehumidify it as well as replace the window that leaked. The risks going forward is to the internal wiring, mechanicals, etc. due to static water exposure for many weeks prior to the sale. Had the dealer done their job with prior inspection, this could have been avoided. I asked them for my money back and they refused so I am stuck with a brand-new car that was essentially flooded with rainwater because the dealer did not do a final inspection prior to my accepting ownership of it. I wrote letter to all the dealership principals involved and NONE of them answered me directly...as if I was invisible or completely silent on this issue. If given an option, I would give them this car back and get a full refund.

The windshield has an optical distortion, characterized by "waviness" and "rippling." This condition is not merely a cosmetic imperfection; it is a safety hazard that causes visual impairment, and dizziness while driving. This defect compromises my ability to perceive distances and hazards accurately, especially when looking through the passenger side while making turns or looking for hazards. Current Status of the Issue as reported online Documented reports indicate that GMC dealers are aware of these "warped windshields" and that the issue appears to be a systemic quality control failure in the 2026 model year. • Safety Risk: This distortion constitutes a safety-related defect as defined by the National Highway Traffic Safety Administration (NHTSA), as it interferes with the driver's primary field of vision. •Failure of Prior Remedies: I am aware that many owners have undergone multiple replacements only to have the same defect reoccur, suggesting that current replacement stock may also be compromised

The contact owns a 2023 GMC Terrain. The contact stated that while driving on several occasions at various speeds, the check engine warning light illuminated, the message "Engine Power Reduced" was displayed, and the vehicle lost power. The vehicle stalled on three separate occasions. The vehicle was able to restart each time after approximately 15 minutes of waiting, but the vehicle failed to accelerate above 40 MPH. The vehicle was taken to a dealer and DTC: P228C, P0089, and P006C were retrieved, and the contact was informed that the fuel pump and fuel injectors needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was unknown.

The contact owns a 2026 GMC Terrain. The contact stated that there was an abnormal clunking sound coming from the front driver’s side suspension while driving over bumps in the roadway, and while braking and turning the steering wheel. No warning lights were illuminated. The vehicle was taken to a local dealer, where a test drive was performed; however, the dealer was unable to determine the cause of the failure. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 14.

The contact owned a 2024 GMC Terrain. The contact stated that while her daughter was driving 5 MPH on an intersection, another vehicle driving 40 MPH crashed into the driver's side of the vehicle, by the driver's side door. The driver's side curtain air bag deployed. The contact stated that the three holes on the air bag propelled burning air, which melted and burned through the three layers of clothing of the driver. The driver sustained second-degree burns and blisters on the hip. The contact picked up and transported the driver to Urgent Care, where medical assistance was provided. A police report was filed. The vehicle was deemed a total loss by the police officer. The vehicle was towed to a tow lot, pending assessment from the insurance company. The dealer and the manufacturer were not yet contacted. The failure mileage was approximately 55,000.

See attached document for complaint.

this just started on it's own. back up rear camera shows distortion from time to time and appears to be getting worse or happening more.

The contact owns a 2023 GMC Terrain. The contact was informed by his wife that while attempting to accelerate from being stationary, the vehicle was shaking abnormally and hesitated before accelerating. There were no warning lights illuminated. The vehicle was taken to the dealer to be diagnosed but the cause of failure was not yet determined. The vehicle was not repaired. The manufacturer was informed of the failure. The manufacturer opened a case for the failure. The failure mileage was approximately 13,000.

Took dealer 3/26 for Sam issue Engine Power reduced after already cause me hit curb. Got it out 4/1/26 Now 4/5/26 it happened again same codes after they claimed they fixed it. Also keep having Emergency services come on a caused my dashboard out. My issues is car keeps stalling losing power. Same codes as week ago after dealer fix. Also 4 time took for noises in my car from passenger side. They keep telling me they can’t replicate it, but you can clearly see where the door is not lined up. This has been going on for over 30,000 miles for that. Like some of these issues have been going on since the 36,000 but now I’m having issues where I’m losing power like this is insane all before 60,000 miles which I’m about to hit. It’s gonna end up getting me killed on the interstate. My vin also says it’s fwd it’s awd AT4 . Called dealer said only to update software clearly not the issue. My doors are off and they have refused to fix those for over 30,000 miles now. It won’t let me attach any pics for some reason I’ve tried since yesterday

Took dealer 3/26 for Sam issue Engine Power reduced after already cause me hit curb. Got it out 4/1/26 Now 4/5/26 it happened again same codes after they claimed they fixed it. Also keep having Emergency services come on a caused my dashboard out. My issues is car keeps stalling losing power. Same codes as week ago after dealer fix. Also 4 time took for noises in my car from passenger side. They keep telling me they can’t replicate it, but you can clearly see where the door is not lined up. This has been going on for over 30,000 miles for that. Like some of these issues have been going on since the 36,000 but now I’m having issues where I’m losing power like this is insane all before 60,000 miles which I’m about to hit. It’s gonna end up getting me killed on the interstate.