C05C3 code meaning
Brake Booster Motor A Supply Circuit
What C05C3 means
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.
C05C3 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C05C3
- 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
Common causes of C05C3
- Most 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
- Less likelyInternal supply path of the brake module damaged
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Brake booster motor a supplyFuseElectric brake booster
What each part of C05C3 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| C3 | The exact fault in that area. |
What to do next
- Note C05C3 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C05C3
What does C05C3 mean?
C05C3 means "Brake Booster Motor A Supply Circuit". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with C05C3?
Drive gently and only to a workshop. With C05C3 the car can go into limp mode (reduced power) to protect itself.
Will C05C3 fail an emissions test?
C05C3 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C05C3 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will C05C3 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.