2021 GMC Terrain Reliability Report

Two of the three reports involve crashes with injuries. In one, the car accelerated hard as the brake pedal was released. In the other, the pedal did not respond on a steep downhill, even when pumped. Neither car was diagnosed. The third complaint is a noisy right rear brake when the car moves forward or backward after sitting. The dealer calls it an ongoing GM investigation, and the noise has persisted since purchase. Rear brake squeaking and grinding also shows up in electrical complaints.

Power cuts out suddenly while driving, with a "reduced engine power" warning and the check engine light. The car barely accelerates, chugs, or revs high. One car went into limp mode twice in freeway traffic, and a turbocharger underboost code was pulled. The warning can clear on its own by the next day before the fault returns, so a short test drive can miss it. Losing power at highway speed is the main safety concern.

The main complaint is hard shaking through the floor or a wobble under acceleration, reported at 45,000 and around 64,500 miles. In one case the dealer replaced both front axles under warranty, which stopped the shaking, and also replaced a leaking driver-side axle seal. Another car wobbles between 40 and 55 mph under hard acceleration even though its tires were balanced and the front end checked out. Reports also mention parking assist symbols going missing and washer fluid that will not spray in cold weather.

Stalling is the common thread. Cars quit at low speed, at a traffic light, and while driving, sometimes with no warning light. One stall at about 86,000 miles was traced to a failed fuel pump that also damaged the camshaft, and the owner linked it to GM recall N222372310 for inadequate fuel pump flow. Another car sometimes will not start from the push button and drains its battery, and the dealer could not reproduce the fault.