C05B4 Brake Booster Temperature Sensor C Circuit High
What does C05B4 mean?
C05B4 — Brake Booster Temperature Sensor C Circuit High. This is an OBD-II diagnostic trouble code a scanner retrieves when your vehicle's computer detects brake booster temperature sensor c circuit high. The level of risk depends on how the vehicle is currently running and how long you've been driving with the light on.
Common causes of C05B4
- Faulty wheel speed or chassis sensor
- Damaged wiring, connector, or corrosion in the sensor circuit
- Worn wheel bearing or damaged tone ring affecting the sensor gap
- Chipped or contaminated sensor reluctor wheel
- Failed ABS or chassis control module
How to fix C05B4
These are general steps for this system. The exact cause depends on your vehicle — confirm with live scan data before replacing parts.
- Scan the chassis/ABS module for specific fault codes
- Inspect the affected sensor, wiring, and connector
- Read individual wheel speeds with an OBD-II scanner during a roll test
- Check the wheel bearing and reluctor ring condition
- Replace the failed sensor or component after circuit tests