OBD-II Code P0850 is defined as a Park/Neutral Switch Input Circuit
The engine computer (PCM) needs to know when the transmission is in Park/Neutral, as this is required before the vehicle can safely be started. The PCM depends on the park/neutral safety switch to communicate when the transmission is in Park/Neutral. If the Park/Neutral Safety Switch fails to operate properly, code P0850 will be set. The engine may be disabled from starting.