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.
The worst 2021 GMC Terrain problems
Ranked by number of owner complaints. Mileage and cost come from what owners wrote.
Problems by type
Tap a problem to see which part fails, at what mileage and in which other years.
- Engine11
- Brakes8
- Transmission8
- Electrical7
- Driver assistance4
- Fuel system4
- Suspension2
- Acceleration1
- Airbags1
- Steering1
- Visibility1
Specific symptoms reported on the 2021 GMC Terrain
Recalls 2
Child seat: vehicle latch anchor
- What is wrong
- General Motors, LLC (GM) is recalling certain 2020-2023 Chevrolet Equinox and GMC Terrain vehicles. The four rear-seat lower child seat LATCH anchorage bars may have excessive powder coating, which could prevent a child seat from being installed with the anchorage bars. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 225, "Child Restraint Anchorage Systems."
- Risk
- The inability to install a child seat with the LATCH anchorage bars could result in an unsecured child seat, increasing the risk of injury in a crash.
- Remedy
- Owners are advised to install child seats using the vehicle's rear seat belts until the remedy is complete. Dealers will inspect the latch anchorage bars, and remove and replace the finish, as necessary, free of charge. Owner notification letters were mailed June 2, 2023. Owners may contact Chevrolet customer service at 1‑800‑222‑1020 or GMC customer service at 1‑800‑462‑8782. GM's number for this recall is N232403240.
Recall number 23V339000 · Recall details
Tires: tread/belt
- What is wrong
- General Motors, LLC (GM) is recalling certain 2021-2022 Chevrolet Equinox and GMC Terrain vehicles equipped with certain Hankook tires. The tires may have been manufactured with an insufficient amount of curative agent, which could cause tread separation.
- Risk
- Tread separation can result in a loss of vehicle control, increasing the risk of a crash.
- Remedy
- Dealers will inspect the tire DOT numbers, and replace any affected tires, free of charge. Owner notification letters were mailed on August 31, 2021. Owners may contact GMC customer service at 1‑800‑462‑8782; and Chevrolet customer service at 1‑800‑222‑1020. GM's number for this recall is N212343560.
Recall number 21V612000 · Recall details
Technical service bulletins for the 2021 GMC Terrain 697
Bulletins tell dealers how to fix known problems. A warranty extension means the manufacturer pays for that repair for longer.
- This service bulletin provides information about GM Accessories
- • Improvements to OnStar functionality.
- This PI provides Diagnostics tips on how the LIN bus works and how to diagnosis it.
- Unknown or other
- Unknown or other
- PI to help diagnose A/C concern
- Unknown or other
- Pi created to provide GM dealers with information on gathering information for projection issue
- Unknown or other
- Unknown or other
2021 GMC Terrain fuel economy
Official EPA estimates in miles per gallon (MPGe for electric). Ranges cover trims that share the same engine.
| Engine | Drive | City | Highway | Combined |
|---|---|---|---|---|
| 1.5L 4‑cyl | FWD | 25 | 30 | 27 |
| 1.5L 4‑cyl | AWD | 25 | 28 | 26 |
What 2021 GMC Terrain owners say
Most recent owner complaints, unedited.
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 the federal safety agency immediately investigate the engine-destroying defects inherent to the 2018–2022 GMC Terrain line to protect consumers from catastrophic highway power failure.
Vacuum pump failure caused my brakes to lock up and almost caused me to wreck into another vehicle
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
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.
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.
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
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.
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.
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.
Compare the 2021 GMC Terrain
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Other model years
201020112012201320142015201620172018201920202021202220232024202520262027
Questions about the 2021 GMC Terrain
Is the 2021 GMC Terrain reliable?
Owners have filed 36 complaints about the 2021 GMC Terrain, fewer than a typical Terrain model year.
What is the 2021 GMC Terrain year score?
The 2021 GMC Terrain scores 87 out of 100 (good). The score compares it with the other model years of the GMC Terrain: 75 is a typical year, 50 means twice the usual complaints, and serious complaints and recalls lower it.
What is the most common problem with the 2021 GMC Terrain?
Engine and cooling, with 11 complaints. Next is brakes (8).
How many recalls does the 2021 GMC Terrain have?
2 recalls, covering child seat and tires.
What year does the GMC Terrain have bad engine?
The GMC Terrain model years with the most engine complaints are 2013 (206 complaints), 2011 (199 complaints) and 2012 (173 complaints).
What gas mileage does the 2021 GMC Terrain get?
Official estimates for the 2021 GMC Terrain range from 26 to 27 mpg combined. The most efficient version (1.5L 4-cyl, FWD) gets 25 city and 30 highway.
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