2018 GMC Terrain Reliability Report

Panoramic sunroof glass shatters with a loud bang while driving, in one case at 2,040 miles. The rest of this category is a mix of problems. Backup cameras haze over behind the lens, headliners sag and block the rear view, and auto stop works erratically and has no off switch. Several reports describe a transmission that will not shift, or a vehicle that shuts down at a light and logs an ECM code. A few more repeat the brake booster and vacuum pump failure, including one booster code that appeared at 460 miles.

An Engine Power Reduced warning followed by a stall, sometimes in moving traffic, is the main pattern. Dealers often blame a cracked vacuum pump that damages the camshaft or sensors, and several engines need full replacement. Many drivers say no warning light came on first, and some had to swerve into a median to avoid a collision. Diesel owners report catalytic converter failures and heavy blow-by. In one case, a converter failed at 101,650 miles and the dealer had no replacement part. Auto stop also draws complaints about hesitation and lurching on restart.

Airbags that fail to deploy in serious collisions make up most of the crash reports. These include driver-side impacts at highway speed, a frontal hit, and a deer strike. Six of the 11 reports involve crashes. One side curtain airbag reportedly burned through clothing and caused 2nd to 3rd degree burns. The rest describe a Service Safety Restraint System warning and airbag light that comes and goes. In one case, a dealer found a failed driver's side front impact sensor. Owners who bought used are often unsure whether a 2018 recall covers their vehicle.

Power steering assist cuts out with a Power Steering Reduced message, or the wheel feels heavy and will not return to center. In one case, a dealer recalibration helped for only about a month. Two crash reports involve sudden loss of control, with 2 people injured. In one, the vehicle veered right and rolled. The other was blamed on a ball joint failing during a turn. Other complaints describe the wheel snatching back in reverse while several warnings light up, and snow packing into the wheels and causing shimmy at highway speed.

Fuel leaks lead this small group. One report describes a steady drip from the fuel tank and cites a recall for the same model year. Diesel fuel line leaks were reported on more than one fleet vehicle. Another report describes turbo failure with power loss, whining or grinding noises, blue smoke, and a check engine light. One more objects that auto stop shuts the engine off at stop signs, then lags before restarting when pulling into traffic.

At night, the backup camera display stays at full daytime brightness. The glare reflects off the windows and makes it hard to see out while reversing. In one case, the problem showed up at about 300 miles, and the dealer confirmed it but said there was no remedy. Other reports describe headliner fabric that comes loose from the panoramic roof track and hangs down, blocking the rear view. One owner says false forward collision alerts started after the headliner dropped.

Seat height adjustment causes most of these few reports. In one, a manual lift lever keeps coming off its track and needed a second dealer visit. In another, a driver seat will not raise for better visibility. The most serious report describes a bolt snapping on the front passenger seat frame with a loud pop, leaving the seat rocking back and forth before the vehicle had moved.