The contact owns a 2017 Ford Fusion. The contact stated that while his son was driving at an undisclosed speed, the check engine warning light illuminated. The vehicle was taken to the dealer and was diagnosed with coolant intrusion into the head gasket, causing engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired due to the new engine not being available. The manufacturer was made aware of the failure and referred the contact to the NHSTA Hotline for assistance. The approximate failure mileage was 50,000.