The contact owns a 2014 Ford Mustang. The contact stated that while driving approximately 80 MPH, the transmission unexpectedly downshifted from fifth gear to first gear, causing the vehicle to abruptly decelerate. After turning off and restarting the vehicle, the vehicle operated but in LIMP Mode. The vehicle was taken to the local service center who diagnosed that the wheel speed sensor and lead frame needed to be replaced. The vehicle was not repaired. The local dealer and manufacturer were notified of the failure, but no assistance was offered. The failure mileage was 140,000.