Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Brake Vacuum Sensor
The sensor is a linear pressure sensor of analogue type and measures the vacuum pressure in the brake booster. Engine Control Module (ECM) monitors the signal from the sensor by reading in the voltage level from the sensor's output signal and converting it to a corresponding pressure. The brake vacuum sensor is supplied with voltage 5 V and is grounded in the Engine Control Module (ECM).
If Engine Control Module (ECM) registers a too low vacuum pressure during driving, activation of the function for automatic start/stop of engine will not be permitted (blocked autostop). If Engine Control Module (ECM) registers a too low vacuum pressure during the time that the function for automatic start/stop of engine is active (vehicle in autostop), then the function is cancelled and the engine is started automatically (system-requested autostart).
The brake vacuum sensor is located on the brake booster.
The Engine Control Module (ECM) can diagnose the brake vacuum sensor.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.