Conditions for Setting the DTC
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0875 sets when PARK, NEUTRAL, or a forward range is selected and the reverse pressure switch remains in the mechanically closed/electrically on position for a period of time that is calibration dependent.