OBD-II code · Chassis
C004C Brake Booster Motor A Position Sensor Exceeded Learning Limit
Brake booster motor A position sensor learned offset exceeded the allowed 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 C004C?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyCalibration not performed after replacement
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
- 0.5–2 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Booster Motor A Pos Sensor
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.