OBD-II code · Chassis
C05C3 Brake Booster Motor A Supply Circuit
Generic fault on brake booster motor A supply circuit. 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 C05C3?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelySupply wiring or fuse fault
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
- Often, with basic tools
- Typical labour
- 0.3–2 h
- Emissions test
- Usually unaffected
- Parts involved
- Brake Booster Motor A Supply, Fuse
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.