DTC P0850-29: Park/Neutral Switch Input Circuit - Signal invalid: Action

WARNING: This page does not describe the selected car, but rather 12 other vehicles, including the 2015 Jaguar XKR-S, 2015 Jaguar XKR, 2015 Jaguar XK, 2014 Jaguar XKR-S, and 2014 Jaguar XKR. However, it is still accessible from the selected car via links, so may be relevant.

Check Parklock mechanism, If Parklock operation correct suspect the Transmission Control Module. Install a new Transmission Control Module as required, refer to the warranty policy and procedures manual if a module/component is suspect