The contact owns a 2017 Ram 1500. The contact stated while driving with the Adaptive Cruise Control engaged and set to 70 MPH, the engine was misfiring and made abnormally loud sounds. Additionally, the vehicle started losing motive power. The message "Service DEF System - See Dealer" was displayed. The contact was able to pull to the side of the road. The contact stated that upon opening the hood and lifting the engine cover, she noticed that the engine was on fire. The contact was able to extinguish the fire with water bottles. There was no Fire or Police report filed. There was no injury sustained. The vehicle was towed to the dealer to be diagnosed. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 95,000.