2015 GMC YUKON DENALI

ENGINE AND ENGINE COOLING

The contact owns a 2015 GMC Yukon Denali. The contact stated that while driving 80 MPH, the vehicle hesitated, and failed to accelerate as intended while depressing the accelerator pedal. In addition, there was an abnormal knocking sound coming from underneath the passenger’s side of the vehicle. The check engine warning light was illuminated. The contact arrived at the residence and used a personal diagnostic reader and retrieved information related to misfires in cylinder #2 and #4. The contact replaced the spark plugs and the ignition coils. The contact test drove the vehicle, and the check engine warning light later illuminated. The contact swapped the ignition coils; however, the failure persisted. The vehicle was taken to the dealer where it was diagnosed that Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) had failed and caused the lifters to fail. The vehicle was not repaired due to the cost. The vehicle remained at the dealer unrepaired. The manufacturer was made aware of the failure but offered no assistance. The failure mileage was approximately 96,000.