Vacuum Pressure Sensor
WARNING: This page is about a different car, the 2018 Jaguar XE and 2017 Jaguar XE. However, it is still accessible from the selected car via links, so may be relevant.
On vehicles with the stop/start system, the vacuum pipes incorporate a brake vacuum sensor with an integral check valve. The brake vacuum sensor monitors vacuum reserves in the brake booster and is hard wired to the Powertrain Control Module (PCM).