C05AF: Brake Booster Motor B Current Sensor Circuit Range/Performance
Standardized SAE J2012 code · C05xx codes
Safety-critical system. Faults in airbags, brakes, steering or high-voltage components can put people at risk. Follow the manufacturer's service information and safety procedures, or have the vehicle checked by a qualified workshop.
What does C05AF mean?
Brake Booster Motor B Current Sensor Circuit Range/Performance: the signal is implausible or outside the valid range. The electric brake booster generates the braking assist; a motor or sensor fault can reduce or disable power-assisted braking. Safety-relevant.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Common causes
- High Sensor reading drifted
- Low Sensor element aged beyond calibration window
- Low Sensor mounting loose - signal damping
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of C05AF on the same make and model first.
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