Brake Vacuum Sensor

WARNING: This page is about a different car, the 2018 Jaguar XE. However, it is still accessible from the selected car via links, so may be relevant.

To make sure that the brake system is never compromised, a brake vacuum sensor is installed to monitor vacuum reserves in the brake booster. The brake vacuum sensor is mounted on the brake booster and hardwired to the Anti-lock Brake System (ABS) control module. If the brake vacuum decreases below a set threshold while auto stop/start function is enabled, the Powertrain Control Module (PCM) either:

Restarts the engine to replenish the vacuum reserves.
Inhibits the engine shutting down if vacuum reserves are not sufficient.

An example of vacuum depleting is when the driver repeatedly pressing the brake pedal while the engine stopped during an auto stop/start stop cycle. This action will initiate an engine restart when vacuum decrease below the set threshold.

If a fault develops with the brake vacuum sensor a Diagnostic Trouble Code (DTC) will be logged in the PCM.