What does code C05B9 mean?

Q: What does code C05B9 mean?

Brake Booster Motor A Position Sensor Supply Circuit Low. This code means the brake control module has detected an abnormally low voltage on the supply circuit that feeds the position sensor inside the brake booster motor assembly. The module expects a stable reference voltage on that sensor's power wire, and when the signal falls below the calibrated threshold, it stores C05B9 and typically disables the affected booster assist function.

DTC codes / C05xx · Brakes, steering and suspension / C05B9

C05B9Brake Booster Motor A Position Sensor Supply Circuit Low

This code means the brake control module has detected an abnormally low voltage on the supply circuit that feeds the position sensor inside the brake booster motor assembly. The module expects a stable reference voltage on that sensor's power wire, and when the signal falls below the calibrated threshold, it stores C05B9 and typically disables the affected booster assist function.

SystemChassis

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaBrakes, steering and suspension

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.