The contact owns a 2021 GMC Yukon. The contact received notification of NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. While the contactas partner was driving approximately 45 MPH, the vehicle started making a rattling sound coming from the front end of the vehicle. The driver pulled over to the side of the road and waited before restarting the vehicle. The contact stated that a quarter mile later, while idling at a stop, the vehicle suddenly lost power. There were no warning lights illuminated. The vehicle was towed to the dealer to be diagnosed and the contact was informed that the engine needed to be replaced; however, the vehicle was not repaired. The manufacturer was not made aware of the issue. The failure mileage was approximately 138,000.