C05CB

Brake Master Cylinder Piston Position Sensor A Circuit Voltage Low

Severity

🔴 High

Can you drive?

Do not drive — repair immediately

Approx. repair cost

$56–167 (est.)

Symptoms

The brake system fault light comes on
Reduced braking performance
Activation of the ABS/ESP system for no apparent reason
Unstable brake operation

Causes

Open or short circuit in the sensor wiring harness
Piston position sensor malfunction
Poor contact in sensor connectors
Malfunction of the brake control unit (ECU)

How to Fix

Check the sensor wiring harness for breaks and short circuits
Check sensor connectors for oxidation and poor contact
Replace the piston position sensor if it is faulty
Check and, if necessary, replace the brake control unit (ECU)

Related codes

C05CC C05CD C05CE