C058C code meaning
Brake Booster Motor B Position Sensor Circuit Low
What C058C means
C058C applies when the motor B position signal sits below its lower limit – usually a sensor line shorted to ground, a missing sensor supply or a damaged sensor element. No manufacturer publishes this code; GM limits its documented position checks to motor A, where C0588 trips in the XT4 module below 1,300 counts. The physics are the same on either side: Hitachi's resolver patent attributes a reading near 0 V to a ground short, and a vector-length check like the one Infineon specifies for its TLE5009 sine/cosine sensor exposes an amplitude that has collapsed. In a dual-winding booster as described by Hyundai Mobis, the inverter for winding B depends on this angle, so the module shuts that inverter down and relies on the remaining channel.
C058C at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C058C
- Brake warning lamp
- Assist may continue on one channel with reduced dynamics
Common causes of C058C
- Most likelySignal line of sensor B shorted to ground
- PossibleSupply of sensor B missing or too low
- Less likelySensor element B or its magnet degraded, signal amplitude too small
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Booster motor b pos sensorSensor wiring
What each part of C058C means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 8C | The exact fault in that area. |
What to do next
- Note C058C 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 C058C
What does C058C mean?
C058C means "Brake Booster Motor B Position Sensor Circuit Low". C058C applies when the motor B position signal sits below its lower limit – usually a sensor line shorted to ground, a missing sensor supply or a damaged sensor element. It is a generic code, so it means the same on every make.
Is it safe to drive with C058C?
Drive gently and only to a workshop. With C058C the car can go into limp mode (reduced power) to protect itself.
Will C058C fail an emissions test?
C058C 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 C058C to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will C058C clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.