2021 GMC Sierra 1500 engine problems

275 owner complaints filed with NHTSA name the engine on the 2021 GMC Sierra 1500 — 52% of all complaints for this model year.

275

Engine complaints

52%

share of all complaints

57,000 mi

median reported incident mileage

0 / 5

crash / fire reports

What owners report

“Engine temp rises way above mid-level and will stay there for several minutes before cooling back down to normal temps. 2 different mechanic shops have told me it's the coolant control valve, but want $2500 to fix it. This service bulletin is for the same year, make, model, and motor as my truck…”
filed Jul 31, 2026
“P1010 and P2B86 engine code, constant cooling fan on engine. Confirmed by dealership, quoted for coolant control valve. VIN not included in special coverage N252508341 for this known issue. Limited engine power alert, unable to maintain speed on highway. Dangerous condition traveling under speed…”
filed Jul 31, 2026
“2021 Harley Davidson Sierra 4WD, 6.2L L87. Started the truck in the morning and immediately heard intermittent, very loud banging noise coming from engine. Shut truck down quickly and had it towed to dealer. Diagnosis was bent pushrods & failed lifters which were replaced under warranty. Factory warranty expired only…”
filed Jul 30, 2026

Verbatim excerpts from complaints filed with NHTSA. Reports are not independently verified.