GMC Terrain transmission problems

POWER TRAIN

Avis Rental. Vehicle simply shut down while driving and would not re-start. Vehicle could NOT be put into neutral to move from roadway. Emergency services vehicles had to remain on site awaiting tow vehicle. Very dangerous situation.

NHTSA complaint #11763641 — an unverified report by a vehicle owner.

POWER TRAIN

Having the start stop issue on my terrain and recently over the last few months, it has been using oil everything that sounds exactly like the recall but mine is not included. My start stop is not working and I have to get him since it had only 60,000 miles on it years ago, but nothing was done.

NHTSA complaint #11762749 — an unverified report by a vehicle owner.

POWER TRAIN

Factory powertrain programming actively locks out 9th gear (overdrive) during freeway driving at speeds exceeding 60–65 mph. The vehicle refuses to upshift from 8th to 9th gear, forcing sustained high-RPM operation during standard highway cruising.

NHTSA complaint #11761243 — an unverified report by a vehicle owner.

POWER TRAIN

Two problems with this vehicle: 1) Transmission occasionally slips on the 2-3 shift which the dealer says he cannot duplicate. Vehicle was brought in four times for this problem. According to the dealer GM corporate has stated the transmission is working within normal parameters, since no codes were found. 2) Vehicle auto braking randomly slams on the brakes with nothing in its path. Dealer states turn off system to just Alert only not Alert and Brake. No codes were set. Fortunately no one was behind me as this could have caused me to be rear ended by another vehicle. In both cases it appears that if no codes are set the problem does not exist. Nov. 21, 2025, Feb. 12, 2026, July 09, 2026, Aug. 28, 2026.

NHTSA complaint #11760586 — an unverified report by a vehicle owner.

POWER TRAIN

The car suffered a long crank, then stalled completely while moving on a public road, which is a severe safety hazard.

NHTSA complaint #11755736 — an unverified report by a vehicle owner.

POWER TRAIN

Because of the intentional failure of GMC and there promise of “We are Professional Grade”, I almost got plowed down by a semi when the car began to quit on the highway going 60. After pulling into the next driveway, which happened to be a Parker’s Kitchen, and ending up on the curb spot, thanking God I wasn’t dead, I sat there for a moment wondering what just happened. As I went to restart the car, it wasn’t having any of it. 40,000 miles, not professional grade GMC, circus grade. Towed it to my home, figuring it has to be something minor and a diy fix. Bought the hyper-tough code reader delivered by Walmart and it delivered professional grade results: U18A2, P1787 and P187E. I am beyond pissed. I could have died due to your intentional negligence in manufacturing. I have a car that will not start, with payments. I have searched the internet and found your “save ourselves plan” and let’s do a voluntary recall starting with 2021 on the same failed parts I am dealing with at the moment. Thanks GMC, who is the ringleader of your circus?

NHTSA complaint #11755143 — an unverified report by a vehicle owner.

POWER TRAIN

The contact owns a 2023 GMC Terrain. The contact stated that while driving at various speeds, the vehicle unexpectedly decelerated and failed to properly accelerate. The service transmission and service fuel management system messages were displayed, and the check engine warning light was flashing with several other unknown warnings illuminated. The vehicle was taken to the local dealer and while test-driving the vehicle, the vehicle stalled. The vehicle was towed back to the dealer. The cause of the failure was not yet determined. The manufacturer was notified of the failure, and an engineer was sent to the dealer to inspect the vehicle. No further information was available. The contact stated that the transmission module was previously replaced, but the failure persisted. The failure mileage was 27,000.

NHTSA complaint #11754923 — an unverified report by a vehicle owner.

POWER TRAIN

adaptive cruise disengaging alert on dash- no cars or weather conditions to induce this. loss of power and bucking on highway( near accident caused) catostostrophic sudden loss of power engine/transmission failure while mechanic driving resulting in car towed back to dealer. loss of power multiple times causing near accidents. sudden jolting at stop light causing car to propel forward requiered both feet on brake pedal to stop. 4 episodes of near collision 1st altert started 04/4/2024 adaptive cruise light on dash 14,700 miles on vehicle 5 episodes continued and now car is still at dealership for emissions failure, loss of power x 4 weeks. ALL PHOTOS OF DASH LIGHTS, REPAIR INVOICES AND VIDEO OF DASH AVAILABLE BUT I AM NOT ABLE TO UPLOAD ALL.

NHTSA complaint #11755131 — an unverified report by a vehicle owner.

POWER TRAIN

Leaking transmission fluid at 7,000 miles. Technicians noticed during routine oil change at dealership.

NHTSA complaint #11749897 — an unverified report by a vehicle owner.

POWER TRAIN

This vehicle was bought new and is a NEW 2026 GMC TERRAIN DENALI with less than 5,000 miles at this time. It is a continuous event and not a specific failure date, but began soon after purchasing. The specific parts are UNKNOWN. It could be tires, wheels, steering parts (CV JOINTS, CONTROL ARMS ETC) or possibly transmission. I took it initially to the purchasing dealership and they took it for a ride and just dismissed the problem without investigating. Several days later I called and talked to the person who sold me the SUV and was told either him or service manager or both would call me, but neither did so. They were to set up a return date. After this insulting experience I decided to take it to a Cadillac dealer that I have had great experience with in the past. They took it for a ride and did experience the problem and investigated what they thought could be causing the SUV to wobble, shimmy, or shaking sensation. This Cadillac dealer said there investigation showed nothing wrong and returned the vehicle to me and said nothing could be done unless GM gave them permission. Next I wrote to the service manager expressing my disappointment in nothing being done and my disappointment in General Motors. There is a Service Bulletin (Document ID: PIT6466). This makes four efforts on my part to get satisfaction with this 2026 GMC TERRAIN DENALI and how it is not fun to drive and there is anxiety on the safety of the vehicle when being driven. *Now for the problem I am experiencing with this 2026 GMC TERRAIN DENALI. There is the sensation of a “wobble, shimmy, or shaking” under low to moderate acceleration when going straight or turning. It could be tires, wheels, steering parts or power train. It is difficult to tell. Sometimes the sensation is as if the wheels will fall off. This is an awful feeling and gives you the feeling the SUV is not safe and it is not fun to drive at all.* Why do I have to drive a brand new expensive SUV and feel unsafe and not enjoy do so?

NHTSA complaint #11748269 — an unverified report by a vehicle owner.

POWER TRAIN

No engine lights are on. When at stops it starts chugging and when I accelerate sometimes it does not go like it should. It idles high and feels like it is slipping. I have almost been hit in the rear several times when this happens. One lady did rear end me but the damage was so little that I did not call the cops. This vehicle has not been inspected and it is available for inspection at any time.

NHTSA complaint #11748117 — an unverified report by a vehicle owner.

POWER TRAIN

The vehicle has experienced a recurring transmission-related defect that has required multiple repair attempts by an authorized GMC dealership. The transmission system has also exhibited fluid leakage. Despite prior repairs, the problem has continued to reoccur. Transmission and associated transmission fluid sealing components. The vehicle is currently available for inspection upon request. A transmission is a critical safety component that transfers engine power to the wheels. A transmission defect or fluid leak can result in loss of propulsion, hesitation, inability to accelerate as expected, unexpected changes in vehicle operation, or transmission failure while driving. These conditions could increase the risk of a crash, particularly when merging into traffic, crossing intersections, or traveling at highway speeds. Transmission fluid leaking onto roadways or vehicle components may also create additional safety concerns. The vehicle has been presented to an authorized GMC dealership for diagnosis and repair on multiple occasions. The dealership has acknowledged and attempted repairs related to the transmission. The vehicle has been inspected and repaired by authorized GMC service personnel. No police involvement. No independent inspection has been performed at this time. Manufacturer-authorized dealerships have documented the repairs. Symptoms included transmission-related concerns and transmission fluid leakage. The defect first appeared while the vehicle was under warranty and has continued despite repair attempts. The recurring nature of the transmission defect and fluid leak has reduced confidence in the vehicle’s ability to operate safely and reliably. The vehicle remains under warranty and has undergone multiple repair attempts without a permanent resolution.

NHTSA complaint #11745857 — an unverified report by a vehicle owner.

POWER TRAIN

Accelerator lag from any speed or stop. The care will take several seconds to hunt for the correct gear before shifting to accelerate. Or it will delay acceleration for several seconds while your pressing the accelerator. No SES indicator active. Mechanics can’t find issues. Other owners on forum a report the same sluggish behavior. These 1.5 turbo cars seem to need a software fix that they are not receiving. It’s like the drive by wire doesn’t register. Affects any gm vehicle with the 1.5 turbo and 9 spd auto.

NHTSA complaint #11744960 — an unverified report by a vehicle owner.

POWER TRAIN

The turbo went completely out at around 105k miles while I was driving to work. I had to coast into a repair shop because it was smoking and wouldn’t go over 20mph and then have it towed to the place that repaired it. Since then, the transmission is having trouble shifting gears. The car struggles to accelerate and I have to go abnormally slow after coming to a complete stop in order for the car to get into gear. The onstar diagnostic says everything is fine but it is clearly not fine.

NHTSA complaint #11743318 — an unverified report by a vehicle owner.

POWER TRAIN

My 2016 GMC Terrain 2.4L Ecotec first stalled while idling at a red light in Raleigh, NC. I restarted it and it sounded different, so I drove it home. The next morning it would not start. The failure occurred at approximately 69,939 miles with no meaningful warning. The dealer’s diagnostic report states there were no current relevant codes and no relevant codes in history. The dealer documented major timing-system failure: timing chain tensioner failure, timing chain guide failure, a timing chain guide bolt pulled out of the cylinder head, aluminum contamination in the cylinder head/oiling system, and engine replacement recommended. The vehicle was found unsafe to operate. This vehicle regularly transported my family, including my children. If the stall/no-start failure had occurred at highway speed, while merging, or in heavier traffic, it could have created a serious crash risk. The oil was maintained outside the dealership network and had been serviced before failure. I also topped off the oil shortly before this occurred. The 2.4L Ecotec engine family is known for oil-consumption issues, yet this vehicle gave me no direct warning that oil consumption had reached a dangerous level. A reasonable owner would not know to check oil every day when there were no relevant stored warning codes. Other NHTSA complaints involving 2016 GMC Terrain vehicles describe similar patterns: oil consumption, no warning lights, sudden stalling or no-start conditions, timing-chain failure, and engine replacement recommendations. I am filing because this appears to be an ongoing safety risk involving oil consumption without adequate warning, timing-chain/timing-guide failure, internal contamination, and sudden engine failure. I request NHTSA review this issue for investigation or recall expansion before this failure mode causes a preventable serious crash, injury, or fatality. The vehicle was inspected by a GMC dealer and remains unrepaired.

NHTSA complaint #11742386 — an unverified report by a vehicle owner.

POWER TRAIN

The contact owns a 2022 GMC Terrain. The contact stated that while driving 45 MPH, the vehicle began to shake independently. No warning light illuminated. The vehicle was taken to the dealer where it was diagnosed that the front drive axel needed to be replaced. The contact was relating the failure to Technical Service Bulletin: 20-NA-227 (wobble or vibration during hard acceleration); however, the VIN was not included in the bulletin. The manufacturer was notified of the failure, and they informed the contact there was no recall for the failure. The failure mileage was 64,000.

NHTSA complaint #11737569 — an unverified report by a vehicle owner.

POWER TRAIN

The car has always had an issue where it would just get stuck in a low gear and RPMs would go high. Does this every single day. But recently it also started acting like it was put into neutral for a few seconds and then back into drive.

NHTSA complaint #11737215 — an unverified report by a vehicle owner.

POWER TRAIN

Car locks itself into 2 Wheel Drive when conditions are "unfavorable" meaning sometimes rain and most commonly in cold weather. If anyone has driven on snowy and icy roads during the winter, they know how much of a problem this can cause in the winter. Not only has the dealership's maintenance department not been able to diagnose the issue but GM themselves are refusing to acknowledge this problem as well. This is a huge safety hazard given the instability of the vehicle driving in those conditions, especially if you cant gain traction while on a busy road. The only indicator is the light that shows AWD and 2WD is in 2WD and an orange color. This is a big accident waiting to happen, if it hasn't happened to someone else already, given the state I've seen some of the newer models in.

NHTSA complaint #11735931 — an unverified report by a vehicle owner.

POWER TRAIN

Automatic transmission solenoid control valve body got stuck open and ruined the whole transmission. This has been a reoccurring problem with these vehicles. Image is from a code read. Issue was confirmed by Gastorf Chevrolet, and an independent transmission shop.

NHTSA complaint #11734629 — an unverified report by a vehicle owner.

POWER TRAIN

The contact owns a 2026 GMC Terrain. The contact stated that while attempting to depress the accelerator pedal after coming from a complete stop, the vehicle started wobbling. A dealer was contacted. The vehicle was taken to the dealer to be diagnosed; however, the diagnostic result was unknown. The vehicle was not repaired. The contact associated the failure with Technical Service Bulletin: PIT6466 (Shimmy, Shake or Wobble When Leaving a Stop); however, the VIN was not included in the bulletin. The manufacturer was notified of the failure and informed the contact that there was no recall for the failure, and opened a case. The failure mileage was 5,200.

NHTSA complaint #11734525 — an unverified report by a vehicle owner.