2018 GMC Terrain: check engine light

Filed Nov 5, 2026 · Fuel system · 106,727 miles · CA

The contact owns a 2018 GMC Terrain. The contact stated that while attempting to start the vehicle, the engine failed to turn over. The contact stated that gasoline was leaking from the engine while refueling. The check engine warning light was illuminated. The vehicle was towed to the residence. A dealer was contacted; however, the vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The contact associated the failure with the federal safety agency Campaign Number: 18V358000 (FUEL SYSTEM, GASOLINE). The failure mileage was 106,727.

Filed Sep 30, 2026 · Brakes, Engine · NY

Without any type of warning, I was driving down the road when my car started making a knocking/ticking type noise then my engine light came on. I attempted to hit my brakes and stop, and I had no control. There was no brakes without pushing it all the way to the floor it was very hard to get my car to stop. I managed to get off the road and into a parking lot and now told that I have $5000 worth of repairs, including the vacuum pump, camshaft timing and guides. After reading information I see there is complaints filed regarding this failed vacuum pump and I would just like to report this.

Filed Aug 3, 2026 · Brakes · 95,300 miles · IL

The contact owns a 2018 GMC Terrain. The contact stated that while driving at an undisclosed speed, the brake pedal was depressed; however, the vehicle failed to stop as intended. The contact stated that the brake pedal was abnormally firm. The brake pedal was depressed to the floor, and the vehicle came to a stop. The check engine warning light was illuminated. The vehicle was towed to the dealer. The vehicle was not diagnosed. The contact referenced an unknown recall; however, the VIN was not associated with a recall related to the failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 95,300.

Filed Mar 6, 2026 · NH

The control knob that controls AWD, 2WD,Off-road, and 4 x4 AWD. Just stopped working. Stuck on 2WD mode. I did have it checked for any codes, even though, there is NO check engine light is on.

Filed Jan 29, 2026 · Fuel system · MI

Turbo boost went out in my vehicle and 3 others with the same engine, different makes/models. Vehicles were serviced at Grayling Car Care 4430 M-72, Grayling, MI 49738 (989) 348-3200. Significant power loss, sluggish acceleration, poor fuel economy, and often strange noises (whining, grinding), accompanied by blue smoke from burning oil and a lit check engine light, with the severe risk of catastrophic engine damage from broken parts entering the engine if driven, requiring prompt replacement. It's generally unsafe to drive with a bad turbo, as metal fragments can destroy the engine.

Filed Nov 21, 2025 · Brakes · 183,000 miles · SC

The contact owns a 2018 GMC Terrain. The contact stated that while driving at an undisclosed speed, the vehicle shuddered and failed to come to a stop while the brake pedal was depressed. The check engine warning light was illuminated. The vehicle was taken to a local independent mechanic, where it was diagnosed with a locked brake vacuum pump. The contact was informed that parts of the brake vacuum pump had entered inside the camshaft and valve cover. Several unknown local dealers were contacted. The vehicle was not diagnosed or repaired because there was no recall associated with the VIN. The manufacturer was made aware of the failure. The failure mileage was approximately 183,000.

Filed Oct 3, 2025 · Brakes, Engine · MN

April 2025, Vacuum Pump went out meaning lost breaks going 60 miles per hour down the road after engine light came on. Left me and two children stranded 2 hours from home with no way to get back except a tow. Now September 2025 Cam Shafts are out as well as Vacuum Pump. Stranded boyfriend and I two hours away again. Now metal in oil and warranty is not willing to cover it due to the vacuum pump going out. Made a post on Facebook and got lots of feedback on how their newer terrains have done the same things. Work in insurance and have people car pertaining to their terrains wondering if we cover engine replacements. There is major issues with these vehicle. Mine only has 107,000 miles on it and I have 12,000 left to pay. The motor is shot and dealership wants to “flush” the metal out of the engine. Very frustrated, I put 12,000 out of my college fund to have a reliable vehicle for my two kids and now this is all I have. A car that doesn’t run. I called warranty and the man I talked to even said that they get a lot of calls for these cars needing to be fixed. I am at a loss on what to do now. The below information about the incident is for the most recent one happening in September. I know that this sounds like a warranty and dealership issue but I guaranty if you send something out to terrain owners they will report major issues that they have had. Leaving them stuck in loans and no where to go.

Filed Aug 7, 2025 · Transmission · CA

I bought this car used and had only had it about a month when I was driving to work and was in slow traffic on the freeway when my car slowed to a stop despite the fact that I had my foot on the gas pedal. It turns out it was a transmission failure. My safety and the safety of the drivers around me were put at risk because I was unable to move my car over to the shoulder and out of the lane of traffic. Traffic was slow but was still moving. My vehicle is available for inspection but I’ve already had it repaired so I no longer have the faulty transmission. The problem was confirmed by an independent service center where I had it repaired. The vehicle was inspected by the dealer and the independent service center. The dealer had it for 12 days but was unable to diagnose it so I took it to an independent service center. It was also briefly looked at and listened to by the highway patrol officer who assisted me and he also thought that the transmission had failed. The check engine light was on when this incident occurred but I was having an issue with one of the glow plugs and I thought that that was the reason. The check engine light came on the night before the transmission failed.

Filed Feb 21, 2025 · Engine, Fuel system · AL

My check engine light comes on intermittently, since March 2024, after having Cabin & Engine air filters replaced. Each time, I’m told it is code P0171. This has happened too many times for my comfort. Usually, it happens around the time my gas gets below 1/2 tank or after I fill up my gas tank. Originally, I was told by the mechanic that it could be one of four things, of which I’ve now had some of things done. InIn Aug. 2024, the check engine light came in. Code was P0171. Mechanic replaced the Brake vacuum pump. Once incident, almost a month later, on 9/24/24, was very scary. While driving on the interstate, I got ready to increase my speed, but heard a pop sound and noticed the speed wouldn’t accelerate. Next, the check engine light came on and the message in the dash popped up saying “engine power reduced” or something similar. I was able to coast from the fast lane over to the slower lane and off the highway into a parking lot. I turned the truck off. When I crunk it back up an hour later, it was shaking and jerking. While slowly driving, on the way to the mechanic shop, it jerked and shook each time I tried to accelerate after stopping at a light or slowing down with traffic. The code again was P0171. According to the mechanic, the intake hose had popped off. On 11/13/24, the check engine light came on. I again took it to have the code scanned and truck looked at. Test results again showed P0171. This time the Mass Air Flow Sensor was suggested. In a year I’ve had the fuel system cleaned twice, brake system flushed, & other routine maintenance such as oil change & brakes. Yet, my check engine light seems to still come on intermittently atleast once monthly. It came on two days ago, 2/18/25, when my gas was around 1/4 tank full. I added a fuel system injector, per mechanic suggestion, and filled my tank up with gas on today, 2/20/25. The check engine light had gone off within about 15 mins of me driving. I’m certain it will be back on soon with the same code.

Filed Jan 23, 2025 · Brakes · FL

I was slowing down to turn and I couldn't push my brake pedal down it completely locked up. If I wasn't already slowing down I would've hit a power pole and potentially lost my life. My ABS light never came on and it's still not on. After I got parked and shut my car off the check engine light came on.

Filed Dec 16, 2024 · Engine, Fuel system · 26,000 miles · FL

The contact owns a 2018 GMC Terrain. The contact stated while driving at approximately 65 MPH, the check engine warning light illuminated, and the vehicle decelerated to 20 MPH. Additionally, the message "Service Emissions" was displayed. The vehicle was taken to the local dealer who diagnosed that the diesel particulate filter was faulty and needed to be replaced. The vehicle was not yet repaired. The manufacturer was notified of the failure, but no assistance was offered. The contact was informed that the VIN was not included in the Extended Warranty coverage for the repair. The failure mileage was 26,000.

Filed Jul 25, 2024 · Brakes, Engine · PA

The vacuum pump gears for the brake assist was shattered and metal parts were sent into the engine. I lost power brakes and was lucky to be able to stop the suv. The car was towed to a GMC dealer where it was diagnosed with a damaged exhaust cam, a shattered vacuum pump and metal pieces in the motor. Cost to fix $3200. This is a 2018 GMC Terrain with 112000 miles on it. I had a powertrane plus warrenty that was still valid but they refused to pay for anything. They claimed the vacuum pump caused the problem and it was not the engines fault. There were no warning check engine lights before this happened.