The contact owns a 2018 Ford F-150. The contact stated while driving 40 MPH, the vehicle inadvertently downshifted and jerked. There was no warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed that the transmission had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure, and a case was opened. The contact was also referred to the NHTSA Hotline for further assistance. The failure mileage was approximately 142,402.