OBD-II code · Chassis
C05B1 Brake Hydraulic Circuit D Leak
Pressure loss in brake hydraulic circuit D.
Is it safe to drive with C05B1?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyBrake fluid leak in circuit D
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–6 h
- Emissions test
- Usually unaffected
- Parts involved
- Brake Circuit D
Related codes
- C055DBrake Hydraulic Circuit B Leak
- C055EBrake Hydraulic Circuit A Leak
- C05B0Brake Hydraulic Circuit C Leak
- C05AEABS Pump Motor Calibration Not Learned
- C05AFBrake Booster Motor B Current Sensor Circuit Range/Performance
- C05B2Steering Wheel Angle Sensor Signal - Yaw Rate Sensor Signal Correlation
- C05B3Brake Booster Temperature Sensor C Circuit Low
- C05B4Brake Booster Temperature Sensor C Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.