2020 GMC TERRAIN Complaints

I am submitting this complaint regarding a serious and dangerous brake failure involving my 2020 GMC Terrain SLT with approximately 150,000 miles. While driving, the vehicle suddenly experienced a vacuum pump failure that caused a severe loss of braking ability with no warning beforehand. The brake pedal became extremely hard, and the vehicle would barely stop. This created a very dangerous situation and could have easily resulted in a serious accident. Thankfully, I was not driving at a high speed when the failure occurred, and there were no vehicles directly in front of me at the time. However, only minutes earlier I had been traveling approximately 65–70 mph on the highway. If this brake failure had occurred while driving at highway speeds or in heavy traffic, I truly believe it could have caused a major crash resulting in serious injury or death. What concerns me most is that there was no warning before the brakes failed. No warning lights and no issues with my brakes. The sudden loss of braking power was extremely frightening and created an immediate safety hazard. After researching this issue, I discovered that other GMC and GM vehicle owners have reported similar vacuum pump failures and brake assist problems. I believe this is a significant safety issue that should be investigated further. Drivers should not experience sudden brake failure without warning, especially on a vehicle that otherwise appeared to be operating normally beforehand. I am very thankful no one was injured in my situation, but I am concerned that another driver may not be as fortunate. My vehicle had to be towed to a nearby shop and they suspected it was the vacuum pump failure and the car started smoking badly. so I had it towed to the GMC dealership and they called me today to confirm that was the problem and it also caused damage to the camshaft. This is a known issue with the terrain and there is currently a class action lawsuit.

The vacuum pump for the brake system failed catastrophically while driving causing damage to the brake booster and lodging metal debree into the engine components. This happened at less than 100k miles on a 2020 gmc terrain.

The contact owns a 2020 GMC Terrain. The contact stated while the vehicle was parked, the contact noticed that the tire well was filled with water. The contact stated that the unknown box on the side was filled with water. In addition, the contact stated that the water dripped onto the ground underneath the rear tire. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was not made aware of the failure. The failure mileage was approximately 70,000.

After vehicle acting like it isnt getting power and trying to die, I pulled into a gas station and turned it off. When I went to restart it, the vehicle kept turning over and over automatically not wanting to start and the engine light came on. I let it sit for about 5 minutes and tried again. It did same thing. I tried a 3rd time pushing the gas pedal and it finally started. I made it home 2 miles away. Turned the car off and tried starting it again with same issues.

Filled up with gas and went to leave gas station and was still rolling to come to a stop and car shut off and would not crank back up o couldn't put in neutral to even move out of the way. After about 10 mins I was able to crank it back up. No lights came or was on and battery was showing 14.5 now that im sitting battery is showing 12.8. Oil was just changed 4 days ago. Just purchased used less then 3 weeks ago. Im at a lost has 122,272 miles on it

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

The article below appears online, 4/13/2026. I have the exact same problem with my 2020 GMC Terrain Denali and I would like other GM vehicles added to their Chevy recall. They use the same parts within GM's product lines. As background info, I went to the dealer, Matick Buick GMC, 29300 Telegraph Rd, Southfield, MI 48034 on Jan. 14, 2026 for repair. I was told water infiltrated my backup camera and its harness. Matick said very few parts are available in the USA. Still not fixed and it is dangerous. Yes is the answer to the 1st 4 general guideline questions. The 5th question is NO. READ MORE TRENDING NEWS: Chevrolet has recalled 271,770 vehicles over an issue with the rearview camera. Some 2023 to 2025 Chevy Malibus were recalled because the camera screen may show a distorted or blank image, the National Highway Traffic Safety Administration said. Dealers will replace the camera at no cost to correct the issue. Owners will get letters in the mail alerting them to the problem after May 18, the agency said. For more information, call Chevrolet at 800-222-1020. The company’s internal recall number is N262551720. The vehicle identification numbers can be searched on NHTSA.gov.

1- at 71,000 miles in 2022 brake vacuum pump “exploded” broke into many small pieces in the middle of driving. Causing brakes to lock. Brake pedal was brick hard. Hard to maneuver the car out of traffic without causing a collision. Luckily car was not being driven at high speed. At time of repair costing $1,000 Mechanic informed me that the pump was made out of a non metal material and he could not fish the small particles out of the motor with a magnet. The motor would need to be taken apart, cleaned out and reassembled….. From this point forward the car drives in “low engine power mode” even with repairs completed and codes cleared. 2- 2 years later the same part “brake vacuum pump” exploded again. Another $1000 repair. At this time we discovered that the fine particles that were not removed from motor has now knocked the timing off by 8%. Also it has caused a knick in a seal causing an oil leak under 100k miles $1800 repair. After these extensive repairs…… The car emits gas fumes into cabin. The smell is so strong it can’t be parked in the garage because it circulates through the house. Even when car is not running. The Car can’t be driven because risk of fire or explosion from gas. Fuel system gets cleaned. Injectors replaced. The car temporarily runs without the gas smell. 2 weeks later the gas smell returns Come to find out the fuel pump failed. Search online and find there is a recall for fuel pumps in this same make model and year. But not this vin number. The car has been a headache from day 1. Recall the whole car at this point, to have so many faulty parts in such major systems of a car is crazy.

Catastrophic engine failure; no warning lights,etc. took place on or about end of January 2026. Car completely died and would not start. Car towed to dealer (GMC Blaise Alexander, Hazleton, PA) Vehicle inspected by dealer master mechanic and others. Engine completely disassembled. Unable to repair. No warnings, lamps, messages or other symptoms prior to failure. Tremendous expense had to be incurred by us over this incident. We had to purchase a new car. Terrain had been meticulously maintained by dealer since purchase. We still had over one year of payments remaining. Expected car to last closer to 200,000 miles. A new engine could have been installed, but cost was too expensive. We lost all of our equity in the vehicle.

The airbag system on my 2020 GMC Terrain has an intermittent malfunction. The airbag warning light turns on and off and the diagnostic code B0014 has been identified by a dealership. When the warning light is on, the airbag system may not deploy properly in a crash, creating a safety risk. The vehicle has approximately 49,000 miles. The problem has occurred for about three years. The dealership repaired the issue when the vehicle was first purchased and the light went off temporarily, but it returned a few months later. A second dealership attempted a repair and again the light went off temporarily before returning. The issue continues to occur intermittently. The warning lamp for the airbag system appears on the dashboard. The vehicle has been inspected by dealerships but the problem has not been permanently fixed.