Problems · NHTSA complaints
2020 GMC Terrain problems
Owners filed 197 complaints about the 2020 GMC Terrain with NHTSA between Nov 2019 and Sep 2026. The most-cited component is service brakes (65).
Complaints
197
Filed with NHTSA
Crashes
7
Reported by owners
Fires
2
Reported by owners
Injuries
5
People reported injured
Deaths
0
Reported to NHTSA
Complaints by component
One complaint can cite several components
- Service brakes65
- Engine58
- Power train28
- Electrical system27
- Fuel/propulsion system25
- Vehicle speed control11
- Forward collision avoidance8
- Service brakes, hydraulic7
- Back over prevention6
- Fuel system, gasoline6
- Structure5
- Engine and engine cooling3
- Air bags3
- Steering3
Complaints are unverified owner reports to NHTSA and are not normalized for sales volume. One complaint can cite several components.
Data from NHTSA Complaints API · synced Oct 28, 2026NHTSA vehicle page
When complaints were filed
Does it get worse with age? Complaints per calendar year filed
1
10
14
13
29
25
63
42
View as table
| Model year | Complaints filed per calendar year |
|---|---|
| 2019 | 1 |
| 2020 | 10 |
| 2021 | 14 |
| 2022 | 13 |
| 2023 | 29 |
| 2024 | 25 |
| 2025 | 63 |
| 2026 | 42 |
Mileage at failure isn’t a structured field in NHTSA complaint data, so we don’t chart it. Some owners mention it in their reports below.
Top problems in owners’ words
Verbatim from NHTSA complaints, newest first
Service brakes
65 reports5 crashes
“While driving at the speed limit the vacuum pump failed on my 2020 GMC Terrain. This failure led to me enter an intersection with heavy cross traffic, nearly striking g several vehicles. This is the 3rd time I have had to replace this pump in 2 years. The pump explodes sending chards of metal into the engine leading to more damage and labor intensive work.”
Engine
58 reports
“While driving my 2020 GMC Terrain, I experienced a sudden loss of normal braking assistance. I had been traveling on the highway and exited onto a main road. As I approached a red traffic light at approximately 50 mph and attempted to brake, the vehicle would not stop normally. I was unable to stop for the red light and went through the intersection before I was able to safely get the vehicle off the roadway. Fortunately, there was no vehicle directly in front of me and I was able to make it through the intersection before any other cars, so no collision occurred. The vehicle was subsequently inspected and diagnosed by a GMC dealership. A diagnostic scan performed after the incident showed code P0556 for the brake booster pressure sensor circuit range/performance. The GMC dealership later diagnosed problems involving the vacuum pump, exhaust camshaft, and timing components and recommended replacement of the vacuum pump, exhaust camshaft, timing components, and related parts.” The sudden loss of braking assistance created a serious safety hazard and could have resulted in a collision, serious injury, or death. The vehicle is currently available for inspection.”
Power train
28 reports1 related recall
“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.”
Electrical system
27 reports1 fire
“The back passenger seat exploded and caught fire, burning the back of the seat in front and burning the ceilings. Inside the whole vehicle is black from smoke damage. Incident assessed by fire marshal who has ruled as electrical issue. No warning lights or systems displayed anything.”
Fuel/propulsion system
25 reports
“Fuel pump control module and or the in tank fuel pump failed and or isn’t making proper connection for car to run correctly. Safety was put at risk as car came to abrupt halt while driving. Driver was outside of vehicle at busy intersection for vehicle diagnostics and battery jump. Battery was removed and new battery installed yet problem persists. Not confirmed by dealer but code is as follows (p129F). Maintenance performed by owner;Code reader used for diagnostics, new battery installed. Problem persists. Car started, drove and stumbled to then die. Check engine now displays.”
Vehicle speed control
11 reports
“Random problems accelerating. Like I can be pulling out of my parking spot in revese then switch it to drive an try to move and it won’t move at all or very slowly then out of nowhere it accelerates fast”
Data from NHTSA Complaints API (owner reports, unverified) · synced Oct 28, 2026
Complaints are unverified owner reports to NHTSA and are not normalized for sales volume. One complaint can cite several components.