OBD-II code · Chassis
C057A Brake Booster Temperature Sensor B Circuit High
Brake booster temperature sensor B signal voltage above expected range. Boost control tracks commanded vs. actual manifold pressure; persistent deviation means wastegate, vanes, hose or actuator are not delivering the requested pressure.
Is it safe to drive with C057A?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySignal wire shorted to battery
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Usually unaffected
- Parts involved
- Brake Booster Temp Sensor B
Related codes
- C05B4Brake Booster Temperature Sensor C Circuit High
- P25C7Brake Booster Temperature Sensor A Circuit High
- C0577Park Brake Force Sensor Circuit Malfunction
- C0578Park Brake Switch Stuck Open
- C0579Brake Booster Temperature Sensor B Circuit Low
- C057BBrake Booster Temperature Sensor B Circuit/Open
- C057CBrake Booster Temperature Sensor B Circuit Range/Performance
- C057DBrake Booster Temperature Sensor Circuit B Intermittent/Erratic
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.