Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with the part of the car that helps you brake easily. It's like the car's computer is saying it can't tell where the brake helper is, so it might not work right.
The code indicates an issue with the circuit that provides power to the position sensor of the brake booster motor. This sensor helps determine the position of the brake booster motor, which is crucial for effective braking.
C05BB is a diagnostic trouble code (DTC) that signifies a problem with the supply circuit of the Brake Booster Motor A Position Sensor. This sensor is responsible for monitoring the position of the brake booster motor, which assists in applying the brakes. A fault in this circuit can lead to improper brake booster operation, affecting braking performance.
• Increased brake pedal effort
• Brake warning light on the dashboard
• Reduced braking performance
• Faulty brake booster motor position sensor
• Damaged wiring or connectors in the sensor circuit
• Malfunctioning brake booster motor
Brake Booster: A device that uses vacuum pressure to assist in applying the brakes.
Position Sensor: A sensor that determines the position of a component, in this case, the brake booster motor.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors related to the brake booster motor position sensor.
• Test the brake booster motor position sensor for proper operation.
• Replace the faulty brake booster motor position sensor.
• Repair or replace damaged wiring or connectors.
• Replace the brake booster motor if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Chevrolet Malibu
• GMC Sierra
• Buick Enclave
• Regular maintenance checks on the braking system.
• Ensure all electrical connections are secure and free of corrosion.
• Replace worn-out components promptly.
Sensor Issue
• Do not ignore the brake warning light.
• Have the vehicle inspected by a professional if braking feels different.
• Regularly test the braking system, especially before long trips.
Check with the vehicle manufacturer for warranty coverage on brake system components.
This code has been reported in vehicles with electronic brake systems, particularly in models with advanced braking technology.
High – Brake system issues should be addressed immediately to ensure vehicle safety.
Driving with a malfunctioning brake system can lead to accidents. It is essential to address brake-related issues promptly.
• Vehicle stationary with engine running
• Perform tests in a safe environment
The brake booster motor and its position sensor are typically located near the firewall in the engine bay, connected to the brake master cylinder.
Q: Can I drive with this code?
A: It's not recommended to drive with a brake system issue, as it can affect your ability to stop safely.
Q: Will fixing this code improve my braking?
A: Yes, resolving the issue will restore proper brake booster function, improving braking performance.
Pro · Four-system diagnostics
A handheld scanner aimed at engine, transmission, ABS, and airbag diagnostic work.
Chassis and ABS faults usually need a scanner that can read brake-system data directly.
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Universal · Torque wrench
Useful when reassembly torque matters for wheel, suspension, and under-hood fasteners.
Useful when wheel, hub, or suspension hardware needs correct reassembly torque.
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Universal · Drive-on ramps
Helpful for safer access underneath the vehicle during exhaust, EVAP, and underbody inspection work.
Helpful for safer access during underbody inspection work.
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