Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2021 GMC Sierra 1500 owners, lightly cleaned up (personal details are redacted by NHTSA).
Less than 5 minutes after my husband and 2 children parked the car and came inside, a neighbor walking rang our doorbell to let us know there was something on fire in our driveway. We ran to the back to find his truck engulfed in flames coming from the engine. We quickly called 911 and exited the house/property. The truck continued to burn with 20-25 foot flames and very black smoke for about 40 minutes until the fire department was able to control the fire. The fire was hot enough that the entire engine was significantly burnt, the seats and steering wheel were gone, the glass shattered and melted, and the tires exploded and melted. Thankfully, everyone was out of harms way and safe through this incident. However, it has been extremely traumatic on my family and neighbors and has taken a lot of time and energy to try to deal with this. …
On [redacted] at approximately 3 pm I left my house and was traveling on [redacted] in Fort Mohave Arizona I was only traveling 7 miles. When I looked at the temperature in the cab was 121 degrees a few moments after the display system went black and never turned back on. I arrived at the store 4 minutes after the display shut off with no warning lights or any type of notification on my phone, I had rolled down the windows to get air in the cab to see if that would help cool down if needed. I was in the store 20 minutes. I returned to the truck turned it on and everything was normal, from there I drove back home nothing happened on my drive back the display was working. At 8 30pm I was traveling on [redacted] Driving towards a casino called Avi. …
The contact owns a 2021 GMC Sierra 1500. The contact stated that upon starting the vehicle, there was an abnormal knocking sound coming from the engine. The abnormal sound ceased once the vehicle had accelerated; however, the abnormal sound returned while the vehicle was idling. The check engine warning light was illuminated. The vehicle was taken to the dealer where it was diagnosed that the ball bearing caused a misfire, and two cam lifters needed to be replaced. The vehicle was repaired. The contact picked up the vehicle and on the way home, the engine failed. The contact took the vehicle back to the dealer. The technician test drove the vehicle with the contact as a passenger, and the check engine warning light illuminated. In addition, there was an abnormal sound coming from the engine. The vehicle failed to accelerate as intended while depressing the accelerator pedal. …
The contact owns a 2021 GMC Sierra 1500. The contact stated that the engine was previously replaced under warranty. The contact stated that the vehicle had been experiencing excessive oil consumption and required three quarts of oil every 30 days. The contact received notification of NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); however, the part to do the recall repair was not yet available. The contact stated that while driving 70 MPH, the vehicle shuddered abnormally and there was an abnormal metallic sound coming from the engine before the vehicle lost motive power. There was no warning light illuminated. The contact was able to pull over to the side of the road. The vehicle failed to restart and was towed to the residence. The local dealer was contacted and informed the contact that a service advisor would return the call. The vehicle was not diagnosed or repaired. …
The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 50-65 MPH on an incline, the contact believed that the transmission was slipping or there was a misfire coming from the engine. The contact stated that the vehicle failed to restart automatically after the engine AUTO Start/Stop system was engaged after a complete stop. Additionally, the contact stated that after driving for a while, the vehicle went into LIMP Mode. The check engine warning light and other warning lights were illuminated. The vehicle was taken to the dealer to be diagnosed. The contact related the failure to GM Campaign Number: N252515590 (Corroded Ground Strap); however, the dealer had informed the contact that the vehicle was not covered because the VIN was not included and there was no warranty coverage on the vehicle. The vehicle was not yet diagnosed or repaired. …
The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign Number: 25V274000(Engine and Engine Cooling); however, the part to do the recall repair was not yet available. The contact stated that while driving at approximately 60 MPH, the check engine warning illuminated and the vehicle stalled. The contact pulled to the side of the road and attempted to restart the vehicle, but the vehicle failed to restart. The vehicle was towed to the residence. The contact stated that the failure had previously occurred several times while driving. An unknown local dealer was contacted and informed the contact that the recall parts were not available. The vehicle was not diagnosed or repaired. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. …
The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign Number: 25V274000(Engine and Engine Cooling); however, the part to do the recall repair was not yet available. The contact stated that while driving 30 MPH, there was an abnormal knocking sound coming from the engine compartment, and the vehicle lost motive power. The contact was able to pull over to the side of the roadway. No warning light was illuminated. The vehicle was towed to a dealer, where it was determined that the engine needed to be replaced. The vehicle was repaired. The contact stated that prior to the engine failure, the transmission was replaced. The dealer was contacted regarding the recall remedy, but the dealer was unable to provide an estimated time of availability. The contact stated that the manufacturer exceeded a reasonable amount of time for the recall repair. …
The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal sound coming from the engine compartment. The contact pulled over to the side of the road and discovered that the engine oil level was low. The check engine warning light was illuminated. The failure occurred on several different occasions. The vehicle was taken to a dealer, where it was diagnosed that the lifters needed to be replaced. The vehicle was repaired; however, the failure persisted. The vehicle was taken to a different dealer (Legacy Westbank Buick GMC; 3611 Lapalco Blvd, Harvey, LA 70058) to be diagnosed. The vehicle was not diagnosed or repaired. The contact was taken to a different dealer (Mossy of Picayune; 241 Frontage Rd, Picayune, MS 39466) where it was diagnosed that the engine needed to be replaced. The vehicle was not repaired. …
The contact owns a 2021 GMC Sierra. The contact stated that while driving at 60 MPH, a reduced power mode warning message unexpectedly illuminated, and the vehicle unexpectedly entered limp mode. The contact stated that the temperature gauge indicated a high temperature and the vehicle was overheating during the failure. The vehicle was taken to the dealer, where it was diagnosed that the control valve had failed and needed to be replaced. The vehicle was not repaired. The dealer informed the contact that this was a known failure and escalated the issue to the manufacturer for further assistance. The contact stated that the failure was associated with Technical Service Bulletin (TSB) N252508340 and believed the repair should have been covered under warranty. The manufacturer was made aware of the failure via telephone and website. …
The contact owns a 2021 GMC Sierra 1500. The contact stated that on Aug. 14, 2025, the PICO engine test was completed on the vehicle under NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling). The dealer stated that the engine had passed the test, and the engine oil was changed to a higher viscosity oil, and the oil cap, oil filter, and the page in the Owner's Manual were updated. The contact stated that the vehicle was making abnormal sounds while idling, and the fuel consumption had increased. The dealer was contacted and advised the contact to bring the vehicle back to have the engine test performed again; however, the contact refused. The vehicle was not repaired. The contact stated that the engine test had not been performed on the vehicle and that the vehicle was unsafe. The manufacturer was informed of the failure and informed the contact that the vehicle was repaired. …
Related recalls
Engine and engine cooling › Engine › Hard parts internal/mechanical
General Motors LLC (GM) is recalling certain 2021-2024 Cadillac Escalade and Escalade ESV, Chevrolet Silverado 1500, Suburban, and Tahoe, GMC Sierra 1500, Yukon, and Yukon XL vehicles equipped with a 6.2L V8 gas engine.
Remedy: Dealers will inspect the engine, and as necessary, repair or replace the engine. For vehicles that pass inspection, dealers will add higher viscosity oil, install 6 oil fill cap, replace the oil filter, and update the…
NHTSA investigations
Loss of motive power due to engine failure post recall remedy
On January 16, 2026, the Office of Defects Investigation (ODI) opened Recall Query RQ26001. This investigation was opened to assess the remedy effectiveness of Recall 25V-274. ODI has received complaints alleging engine failure in vehicles after the recall remedy had been completed, whether that remedy involved an oil viscosity change or a complete engine replacement.
Loss of motive power due to engine failure
On January 16, 2025, the Office of Defects Investigation (ODI) opened Preliminary Evaluation PE25001 after receiving complaints and field reports concerning engine failures in MY2019-2024 GM's full-size truck and SUV T1XX platform equipped with the L87 6.2L V8 engine.
Loss of motive power due to engine failure post recall remedy
On January 16, 2026, the Office of Defects Investigation (ODI) opened Recall Query RQ26001. This investigation was opened to assess the remedy effectiveness of Recall 25V-274. ODI has received complaints alleging engine failure in vehicles after the recall remedy had been completed, whether that remedy involved an oil viscosity change or a complete engine replacement.
Loss of motive power due to engine failure
The Office of Defects Investigation (ODI) has received 1,157 reports of engine bearing failure failures in the L87 6.2L engine produced by General Motors (GM). Of the 1,157 reports received, 173 are outside of the scope of recall 25V-274.
Engine complaints in other Sierra 1500 years
Frequently asked questions
How common are engine problems on the 2021 GMC Sierra 1500?
NHTSA has 367 complaints about the engine & cooling of the 2021 GMC Sierra 1500, 62% of the model year's 594 complaints. The component named most often is cooling system › hoses/lines/piping/fittings (1 mentions).
Is there a recall for 2021 GMC Sierra 1500 engine problems?
Yes — NHTSA recall 25V-274 (hard parts internal/mechanical, Apr 24, 2025). Recall repairs are free at authorized dealers.
At what mileage do 2021 GMC Sierra 1500 engine problems start?
Half of the complaints with a recorded mileage happened before about 59,000 miles, and 21% before 25,000 miles.
Is it dangerous?
Owners linked 0 crashes, 5 fires and 1 injury to engine & cooling problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.