The contact owns a 2018 Ford Fusion. The contact stated while driving at an undisclosed speed, the engine overheated with the check engine warning light illuminated. The contact stated that the message that the engine was overheating was illuminated. The vehicle was restarted after the contact added coolant to the reservoir. The contact stated that after adding coolant to the reservoir, the failure recurred. The vehicle was taken to an independent mechanic, where it was diagnosed that coolant had leaked into the cylinders, causing engine failure. The contact was informed that the engine needed to be replaced. The vehicle was not repaired, and the contact was referred to the dealer for further assistance. The dealer was contacted. The vehicle was not diagnosed or repaired. The manufacturer was made aware of the failure. The failure mileage was 155,000.