C0131
Master Cylinder Pressure Sensor Range/Performance
The ABS or stability control module has detected an implausible signal from the master cylinder brake pressure sensor. This sensor reports driver brake input and is used by ABS and ESP for control decisions.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: medium
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Common causes
Ordered by how often each turns out to be the cause.
- Pressure sensor failedCommon
- Wiring or connector faultPossible
- Air in brake system causing erratic pressureLess likely
Parts involved
- Master Cylinder Pressure Sensor
- ABS Control Module
- Esp Control Module
C0131 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.