2021 GMC Terrain

36 complaints on file, page 1 of 2.

1. Filed Sep 29, 2026Failure May 27, 2026Winfield, MOEngine

   I have had my check engine light come on for P0299. I've lost power while on the road. Had my turbo replaced and now the same issue is starting again. I'm afraid of my car stalling out again with my child in the car. This is a definite safety issue especially since this is happening again months after getting the new turbo put in.

   NHTSA complaint 11767928
2. Filed Sep 11, 2026Failure Jul 22, 2026Aubrey, TXEngine

   Vehicle Information:Year/Make/Model: 2021 GMC TerrainEngine Type: 1.5L Turbocharged EngineCurrent Mileage: 155,000 miles [1]Description of Safety Defect:I am writing to report a severe, sudden engine and turbocharger failure on my 2021 GMC Terrain that presents an extreme, life-threatening safety hazard. While operating the vehicle in active traffic, the engine began flashing a severe dashboard warning reading "Stop Now Danger" (accompanied by low oil pressure alerts) before suffering an immediate, catastrophic loss of all motive power. 2-This unexpected stalling leaves the driver completely stranded on active roadways without warning, drastically expanding the risk of a high-speed rear-end collision. A mechanic has inspected the vehicle and confirmed that both the engine assembly and the turbocharger require full replacement, with a repair estimate totaling $12,000. General Motors is currently facing legal actions regarding defective, camshaft-driven mechanical vacuum pumps and PCV configurations on these 2018–2022 1.5L engines defects known to fracture, send metal fragments violently into the engine top, and trigger immediate engine failure and turbocharger destruction. Despite these severe risks, GMC has refused to provide any goodwill assistance or repairs because the vehicle is outside warranty. I request that NHTSA immediately investigate the engine-destroying defects inherent to the 2018–2022 GMC Terrain line to protect consumers from catastrophic highway power failure.

   NHTSA complaint 11763647
3. Filed Jul 12, 2026Failure Jul 12, 2026Slidell, LAService brakes

   Vacuum pump failure caused my brakes to lock up and almost caused me to wreck into another vehicle

   NHTSA complaint 11749838
4. Filed Jul 1, 2026Failure Jun 28, 2026Colonia, NJService brakes

   Formal Safety Complaint – 2021 GMC Terrain Brake Failure Vehicle: 2021 GMC Terrain Incident Location: Garden State Parkway (NJ) Speed: Approximately 65 mph Incident Description While driving northbound at highway speed, I attempted to change lanes and apply my brakes. When I pressed the brake pedal, it became completely rigid (rock hard) and failed to function. I had no ability to slow the vehicle using normal braking. At that moment, I was forced to: Navigate multiple emergency lane changes to avoid striking other vehicles Prepare for potential collision due to lack of braking control Apply extreme force with both feet on the brake pedal in an attempt to generate any slowing Eventually, I was able to steer the vehicle to the shoulder while exerting maximum pressure on the brake pedal. During the incident, a “Driving Assist Brake” message appeared on the dashboard, and the braking system has remained in this same compromised condition since. Safety Concerns The brake pedal became non-functional without warning The failure occurred at highway speed, creating an immediate life-threatening situation This was not a gradual degradation—this was a sudden, complete loss of braking capability The issue persisted after the vehicle was stopped Broader Concern I have since found multiple reports and videos of other GMC Terrain owners experiencing the exact same failure, suggesting a potential systemic or design-related issue. Given: The severity of braking system failure The apparent repeat nature of this issue The lack of an active recall addressing it I believe this represents a significant safety risk to GMC Terrain drivers and the public. Impact This incident caused: Immediate danger to my life and other drivers Extreme emotional distress Loss of confidence in the safety of the vehicle Requested Action I am requesting: A formal investigation into this braking failure Immediate inspection and repair of my vehicle at no cost Clarification from GMC regarding know

   NHTSA complaint 11747608
5. Filed Jul 1, 2026Failure Jun 28, 2026Colonia, NJService brakes

   Driving on the Garden state parkway on Sunday night June 28, 2026 I proceed to cross over the ratitan bridge. There was traffic as I was going down the bridge at 70 miles an hour. When I applied the brakes the car would not stop. I had two 6 years old in the backseat. I applied 2 feet to the brake pedal and it was like a rock and the car would not slow down. I thought I was going to crash. I had to steer and lane change several times to avoid hitting other cars. This has something to do with the driving assist braking system. I was scared to death. If this isn’t a safety concern nothing is. This should be a recall for GMC to fix because it’s an accident waiting to happen.

   NHTSA complaint 11747599
6. Filed Apr 29, 2026Failure Apr 13, 2026Wright City, MOPower 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
7. Filed Mar 16, 2026Failure Feb 13, 2026Dexter, NYEngine, Turbo/supercharger

   Vehicle went into reduce engine power mode and check engine light came on. Vehicle has just over 60,000 miles. Code is telling me I need a new turbo and being quoted $1,500-$3,000. I have read so many people having the same issue with needing a new turbo just after 60,000 miles

   NHTSA complaint 11724745
8. Filed Mar 16, 2026Failure Aug 1, 2025Baton Rouge, LAEngine

   The contact owns a 2021 GMC Terrain. The contact stated that while driving at various speeds, the vehicle hesitated while depressing the accelerator pedal, with a misfire coming from the engine. During the failure, the message "Engine Power Reduced" was displayed on the instrument panel. The vehicle was taken to a local dealer, and the contact was provided an estimate for a diagnostic test. The contact declined. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was unknown.

   NHTSA complaint 11724576
9. Filed Jan 26, 2026Failure Jan 26, 2026Slinger, WIEngine, Fuel/propulsion system, Blind spot detection

   The engine light came on while driving, saying “engine power reduced”. It barely accelerates, RPMs go over 5, it chugs when driving. Taken to an independent service center.

   NHTSA complaint 11713477
10. Filed Jan 22, 2026Failure Dec 24, 2025Overland Park, KSEngine

    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.

    NHTSA complaint 11712586
11. Filed Oct 31, 2025Failure May 11, 2023Birmingham, ALChild seat

    The contact owns a 2021 GMC Terrain. The contact received notification of NHTSA Campaign Number: 23V339000 (Child Seat); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The dealer was contacted and informed the contact that the vehicle would not be inspected or repaired. The manufacturer was made aware of the issue. The contact had not experienced a failure.

    NHTSA complaint 11696797
12. Filed Sep 17, 2025Failure Jun 20, 202578,843 milesHopkinsville, KYEngine control module (ecu/ecm), Power train, Service brakes

    The contact owns a 2021 GMC Terrain. The contact stated that the transmission was previously replaced. The contact stated that upon starting the vehicle, the check engine warning light illuminated. The failure had occurred intermittently. Additionally, the contact stated that while driving approximately 15-20 MPH and depressing the accelerator pedal, the vehicle failed to respond for approximately 1 minute. The vehicle was taken to the Nissan dealer it was purchased several times. The dealer retrieved diagnostic trouble codes: P057C and P057E, and the brake pedal position sensor was replaced twice; however, the failure persisted. The Nissan dealer took the vehicle to a GM dealer, where the cause of the failure could not be determined. The vehicle was not repaired. The contact related the failure to TSB Number: PIT5994 (Diagnostic Tip for Reduced or Low Engine Power on Acceleration). The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 78,843.

    NHTSA complaint 11687881
13. Filed Aug 3, 2025Failure Apr 1, 2025Buffalo, MNUnknown or other

    Constantly have water leaking into spare tire compartment, back seat floors and passenger floor. Mold/mildew smell coming through vents. Have had drains lines cleaned out, and still recurring having this issue. Unknown where leak is coming from. This is a serious health risk.

    NHTSA complaint 11678054
14. Filed Jul 1, 2025Failure Jun 29, 2025Johannesburg, MIElectrical system, Adaptive cruise control, Automatic emergency braking

    Driving my vehicle with no warnings, messages, or symptoms on adaptive cruise control Sunday [XXX] on [XXX] in Michigan. I changed lanes into the right lane when the vehicle abruptly, without notification, and with force, caused braking that unexpectedly and dangerously slowed the vehicle then released braking before doing the same a moment later. Vehicle was pulled off the road onto the shoulder without an accident, thankfully nobody was behind because they would not have been able to stop in time before hitting my vehicle and I assume the brake lights weren't activated since I did not press the brake pedal either time the vehicle was abruptly slowed causing audible noise of traction loss due to skidding. Vehicle engine would function but parking brake remained active leaving vehicle unable to change gears and transmission warning showed on instrument panel. Vehicle towed to a Chevrolet dealer in Grayling, Michigan where it remains and would be available for inspection. Dealer shows transmission as the cause and in need of replacement. Vehicle has been maintained at GM shops since original ownership. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

    NHTSA complaint 11670483
15. Filed May 28, 2025Failure Sep 19, 2024St Joseph, MOPower train, Suspension

    First time I had problems with my 2021 Terrain I took it to victory GMC on 9/20/24. At the it had 45,000 miles. Every time I would drive and accelerate it would shake extremely bad in the floorboard. There was also transmission fluid leaking. I picked the car up on 9/27/2024 and was advised that both front axles were replaced, which corrected the shaking and the driver side axle seal was replaced, which was where the leak was coming from. this was covered under warranty but at 45,000 miles I should not have been already having axle problems or any type of leak. I dropped my car off again on May 5, 2025. When I called them the day I made the appointment I let them know I had a service transmission message show up and then go away, I told them it’s taking longer to kick into gear when I’m on the highway, I told them it revs up past 4 1/2 RPMS at times when it had not previously done this and it just sounded like the engine is working harder. I also told them I had a check engine line come on and go off and it was code P2271 which was an oxygen sensor code. I also told them when I had the oil changed. They told me there was a slight oil cooler leak starting. All this was supposedly addressed when I dropped it off to be serviced on 5/5/25. I was called on five 625 to pick up my vehicle notifying me that they found no issues. They were unable to verify concern concerning my check engine light. They said there was no oil cooler leaking, it was just slightly seeping, so not considered a leak. And they said no transmission concern operated as designed. Fast forward to May 9, 2025… I got in my car in the morning and once again the check engine light was on. I drove it straight to GMC and had them put the reader on it. The oxygen sensor code came on. The same code I told them about on the 5th that they said was fine on the 6th. I made an appointment once again to get this check engine light looked at although the check engine light is not on at the moment again.

    NHTSA complaint 11663450
16. Filed May 13, 2025Failure Mar 1, 2025Kenmore, NYUnknown or other

    Drive shaft on my GMC Terrain needs to be repaired according to my repair shop. I brought it in as it was vibrating on acceleration and other times frequently. I was told it was the “drive shaft” and the mechanic states they have had Equinox and GMC Terrains coming in for same issue. (Specifically my year Terrain) I looked up and found this recall # for this issue: N212343560. I was never notified and now have a very expensive repair bill which may or may not fix the issue.

    NHTSA complaint 11660584
17. Filed Apr 24, 2025Failure Apr 24, 202536,000 milesEthel, MSEngine, Power train

    The contact owns a 2021 GMC Terrain. The contact stated while driving at various speeds, the transmission erroneously shifted to the neutral, causing the vehicle to decelerate. After restarting the vehicle, the vehicle operated normally. During the failure, the message " Power Reduced" was displayed. The cause of the failure was not yet determined. The local dealer was notified of the failure. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was 36,000.

    NHTSA complaint 11656552
18. Filed Apr 4, 2025Failure Mar 14, 202586,000 milesKissimmee, FLEngine, Fuel system, Fuel pump

    The contact owns a 2021 GMC Terrain. The contact stated while driving 5 MPH, the vehicle stalled. There was no warning light illuminated. The contact stated that the failure was like GM Product Safety Recall: N222372310 (Inadequate Fuel Pump Flow). The vehicle was towed to an independent mechanic, who determined that the fuel pump had malfunctioned and damaged the camshaft. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was not contacted. The approximate failure mileage was 86,000.

    NHTSA complaint 11652800
19. Filed Jan 14, 2025Failure Sep 25, 2024Waterport, NYElectrical system, Engine, Fuel/propulsion system

    I purchased the car August 2024, I have had it for 4 months and while driving down the road a large fuel tank pops up stating low fuel and the car comes to an abrupt stop.The 3x the gas tank was never low. Parking brake comes on and car doesn't not move. All lights on dash come one. It has done it 4 times and thankful each time I was in a 30 mph zone. If I was going 55 I am sure the result would have been bad. The car last did it on December 29, 2024 and has been in the dealership for 3 weeks now and they cannot fix it. I told them 3 days into my purchase I wanted a full refund and they denied me. ?? I had that right I am still fighting with them to take it back because one of these times I am going to get in a bad accident. I don't feel safe in the car and I told them each time.

    NHTSA complaint 11635970
20. Filed Sep 3, 2024Failure Sep 3, 2024Lansing, MIService brakesCrash1 injured

    The contact owned a 2021 GMC Terrain. The contact stated while the brake pedal was depressed, it was released and the vehicle suddenly accelerated aggressively. The contact attempted to avoid crashing into the vehicle in front and swerved however the front of the vehicle still impacted the vehicle in front. The air bags deployed upon impact. A police report was filed. The contact stated no medical attention was provided, but did suffer bruises from the air bag and seat belt. The vehicle was towed to an independent mechanic. The dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was not available.

    NHTSA complaint 11612312