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Brake Pressure Sensor

Measures the hydraulic pressure in the brake circuit and reports it as a number the stability control system can act on.

It is not the brake booster pressure sensor, which reads the vacuum or assistance available rather than the pressure produced. The two are separate parts answering different questions, and confusing them sends a diagnosis to the wrong end of the system.

Stability control needs the number twice over: to know what pressure is already at a wheel before adding more, and to confirm that pressure it applied without the driver's foot actually arrived. Hill-hold, autonomous emergency braking and regenerative blending all read it.

Replacement opens the hydraulic system. The sensor threads into the modulator or a brake line, so the brakes must be bled afterwards — which is why a small, cheap-looking part is a specialist job. Vehicles often fit two and compare them, so a correlation fault means they disagree rather than that either has obviously failed.

Also known as: brake fluid pressure sensor, brake line pressure sensor, master cylinder pressure sensor

Referenced by 42 codes

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Codes involving this component (42)

Other components in Braking, Steering and Suspension

Information, not instruction

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