Federal safety officials are expanding an investigation into 1.27 million Ford F-150 trucks after multiple reports of dangerous transmission issues. The National Highway Traffic Safety Administration (NHTSA) said drivers of 2015–2017 F-150s equipped with “6R80” transmissions reported unexpected downshifts without warning, sometimes accompanied by temporary rear-wheel lockup or skidding, conditions that significantly increase the risk of a crash.

The F-150 remains America’s best-selling pickup, making the potential safety problem particularly concerning. NHTSA first opened a preliminary evaluation in March 2025 following complaints about the 6R80 transmission. The expanded investigation now includes an engineering analysis to test the vehicles and review technical data.

Ford told FOX Business it is cooperating with regulators, noting that the alleged defect in 2015–2017 models differs from earlier recalls covering 2011–2014 trucks, which involved a speed sensor supplied by an outside vendor. The company said the newer issue may stem from electrical connections degrading over time due to thermal cycling and vibration, causing the transmission range sensor (TRS) to lose signal.

In preliminary testing, NHTSA found that TRS signal loss while the vehicle moves up an incline in reverse could shift the truck into neutral, causing it to roll forward. The investigation is ongoing as officials work to determine the full scope and potential remedies for affected trucks.