C05C3Brake Booster Motor A Supply Circuit
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- Points to the power feed of booster motor A: fuse, supply cable, ground or the module input that carries battery current to the motor stage, rather than the motor windings themselves. No manufacturer documents C05C3 publicly. Bosch specifies its iBooster for supply voltages above 9.8 V with up to 450 W of motor power, so a weak feed shows up quickly under load. Hitachi describes cutting the booster motor current when the supply drops below or rises above set limits, and motor gate drivers such as the TI DRV8343-Q1 lock out on supply undervoltage. Check voltage drop on feed and ground while braking. Phase current faults are C0590/C0591, internal driver faults C0595, and the position sensor supply has its own codes.
- What you may notice
- Brake warning lamp, loss or reduction of brake assist
- Hard brake pedal, especially at low battery voltage
- Further faults for regeneration or driver assistance braking
- Likely causes
- LikelyBlown fuse or corroded high-current feed to the booster
- PossibleLoose or corroded ground of the brake unit
- PossibleWeak 12 V battery or charging fault causing voltage dips
- RareInternal supply path of the brake module damaged
- Repair
- Medium · Usually a job for a workshop.Typical cost: €20 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.