The contact owns a 2018 Ford Focus. The contact stated while driving at an undisclosed speed, the transmission unexpectedly downshifted, with the check engine warning light illuminated. The vehicle was towed to an independent mechanic and was diagnosed with transmission failure. The contact was informed that the transmission needed to be replaced. The vehicle was not repaired. The dealer was contacted; however, the vehicle was not diagnosed or repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline for assistance. The approximate failure mileage was 152,910.