DTC P0504-27: Brake Switch A F/B Correlation - Signal rate of change above threshold: Action

WARNING: This page is about a different car, the 2015 Jaguar XF, 2014 Jaguar XF, and 2013 Jaguar XF. However, it is still accessible from the selected car via links, so may be relevant.

Check for related brake pressure DTCs within the anti-lock braking control module
Check brake pedal switch is fitted correctly. Clear DTC, start the engine and press the brake pedal, using maximum travel, for greater than 1 minute taking care not to press the accelerator pedal
Check and install new brake pedal switch as required