2021 GMC Sierra 1500 Engine cooling Problems

“See attached document for complaint. I am writing as the owner of a 2021 GMC Sierra 1500 equipped with the 6.2-liter engine that has recently been included in a significant recall. I've been advised that the engine may need to be replaced entirely. As you can imagine, this is extremely concerning given the scale of the defect and the vital role this truck plays i'n my dayto- day responsibilities.”

“The contact owns a 2021 GMC Sierra. The contact stated that while driving at approximately 40-45, the engine warning light illuminated. There was an abnormal sound coming from the fan. The vehicle was taken to the local dealer, where it was diagnosed and determined that the coolant flow valve needed to be replaced. The vehicle was not included in a special coverage program. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was approximately 50,000.”

“The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 35 MPH, the engine was making an abnormal sound, and the vehicle failed to accelerate. The engine was popping and making cranking sounds, with several unknown warning lights illuminated. The vehicle was driven back to the residence with the issues. The contact referenced NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); as a possible cause for the failure; however, the VIN was not included in the recall. …”

“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 contact owns a 2021 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal clunking sound coming from the rear suspension. The check engine warning light was illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the rear suspension. The vehicle was repaired, but the failure reoccurred 4,000 miles later. The contact stated that while reversing, the contact heard an abnormal clunking sound coming from the rear suspension. …”