C0090
Hydraulic Brake Pressure Sensor Circuit
The brake pressure sensor in the master cylinder or hydraulic block reports an implausible signal or no signal. The fault disables ABS, stability control and brake assist.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: hard
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 element failedCommon
- Sensor wiring faultPossible
Parts involved
- Brake Pressure Sensor
- ABS Control Module
- Sensor Wiring
C0090 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.