2021 GMC Sierra 1500 engine problems
299 owner complaints filed with NHTSA name the engine on the 2021 GMC Sierra 1500 — 53% of all complaints for this model year.
What owners report
“Check engine light came on my vehicle (104,000/mi) and fans came on while truck was off. Took to dealership and techs diagnosed vehicle as having bad "coolant flow control valve". Dealership ran VIN check as there is a GM "extended special coverage program" N252508341 for the LM2 motor, which my…”
filed Sep 11, 2026
“Engine stop working, lots of black smokes through the exhausts and vibrating weird. Lifters failed amoung other parts and they deemed the engine bad so they replaced it with a new one. The new engine started to make the same weird noises.”
filed Sep 10, 2026
Verbatim excerpts from complaints filed with NHTSA. Reports are not independently verified.
Related recalls
- Connecting rod and/or crankshaft engine components may have manufacturing defects that…Campaign 25V274000 · Apr 24, 2025
Engine problems in other Sierra 1500 years
| Year | Reports | Share |
|---|---|---|
| 2026 Sierra 1500 | 74 | 67% |
| 2025 Sierra 1500 | 52 | 45% |
| 2024 Sierra 1500 | 180 | 51% |
| 2023 Sierra 1500 | 204 | 44% |
| 2022 Sierra 1500 | 236 | 40% |
| 2020 Sierra 1500 | 231 | 50% |
| 2019 Sierra 1500 | 299 | 47% |
| 2018 Sierra 1500 | 65 | 22% |
| 2017 Sierra 1500 | 58 | 16% |
| 2016 Sierra 1500 | 38 | 11% |
| 2015 Sierra 1500 | 83 | 12% |
| 2014 Sierra 1500 | 69 | 9% |
Other reported problem areas on the 2021 GMC Sierra 1500
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.