C05BEBrake Booster Motor B Position Sensor Supply Circuit High
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- C05BE is stored when the 5 V feed of motor B's position sensor exceeds its upper limit. No manufacturer documents it publicly. Two mechanisms are typical: the supply line has contacted a wire carrying battery voltage, or the reference ground of the sensor side has lifted, which makes every voltage measured against it look too high. Denso's patent illustrates the ground effect for a sensor read through a pull-down: a broken ground drives the signal above 4.7 V. In Hitachi Astemo's cross-check a rising ground pulls both references down while the monitor values stay put, which separates a ground fault from a true overvoltage. TI's tracker cuts its output path when shorted to battery. The booster then drops channel B and runs with motor A or reduced assist.
- What you may notice
- Brake warning lamp and assist warning
- Possibly further sensor codes if a shared ground is affected
- Likely causes
- LikelyMotor B sensor supply shorted to a battery-voltage wire
- PossibleOpen or high-resistance sensor ground raising the measured voltage
- RareSecond sensor supply regulator out of regulation
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.