C05B9

Brake Booster Motor A Position Sensor Supply Circuit Low

Severity

⚠️ Medium

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$56–167 (est.)

Symptoms

Increased brake pedal force
The brake system fault indicator lights up
Reduced braking performance

Causes

Open or short circuit in the sensor wiring harness
Brake booster motor position sensor malfunction
Problems with power or grounding of the circuit
Malfunction of the brake control unit (ECU)

How to Fix

Check the wiring harness for damage or corrosion.
Measure the voltage in the sensor power circuit
Check the resistance of the position sensor
If necessary, replace the sensor or wiring harness
Check and, if necessary, replace the brake system control unit

Related codes

C05BA C05BB C05BC