2018 GMC Terrain engine problems
53 owner complaints filed with NHTSA name the engine on the 2018 GMC Terrain — 24% of all complaints for this model year.
What owners report
“Approximately 3 miles from my residence my car display flashed "Reduced Engine Power" and slowed down. When I reached a stop sign and tried to stop, my brakes were stiff and I was unable to stop. I went through the stop sign. I continued to my residence at 10mph and backed into a parking space with…”
filed Aug 24, 2026
“While driving my 2018 GMC Terrain, the vehicle suddenly displayed an “Engine Power Reduced” warning and the brakes became extremely hard to press. The vehicle experienced a sudden loss of normal power-brake assist while it was in motion, creating a serious safety risk because significantly greater…”
filed Aug 10, 2026
Verbatim excerpts from complaints filed with NHTSA. Reports are not independently verified.
Engine problems in other Terrain years
| Year | Reports | Share |
|---|---|---|
| 2026 Terrain | 1 | 3% |
| 2024 Terrain | 11 | 22% |
| 2023 Terrain | 14 | 37% |
| 2022 Terrain | 10 | 17% |
| 2021 Terrain | 9 | 26% |
| 2020 Terrain | 57 | 29% |
| 2019 Terrain | 68 | 37% |
| 2017 Terrain | 77 | 58% |
| 2016 Terrain | 46 | 30% |
| 2015 Terrain | 80 | 27% |
| 2014 Terrain | 123 | 42% |
| 2013 Terrain | 197 | 54% |
Other reported problem areas on the 2018 GMC Terrain
Counts are unique NHTSA complaints naming this component group. Complaints are unverified owner reports; mileage is computed only from complaints that included a usable odometer reading.