Downshifting 2013 Volkswagen Passat

2013 VW Passatt 3.6 liter. Transmission started downshifting on its on with wrench light on panel. When I stop car, turn off engine and restart, car drives ok for a while then downshifts again. Whats the problem.

You will need to have it diagnosed. The car’s onboard computer controls the transmission. The computer (PCM) is probably at fault. The wrench light indicates a problem.

A power-train control module, abbreviated PCM, is an automotive component, a control unit, used on motor vehicles. It is generally a combined control unit, consisting of the engine control unit (ECU) and the transmission control unit (TCU).