P0555 fault code usually comes because there is a problem with the brake booster pressure sensor circuit. The brake pressure sensor itself may malfunction, the connector can be faulty or corroded, wires to the sensor can get damaged, or there is a problem with the Engine Control Module (ECM / ECU / PCM).
In addition to P0555, you may get other related codes such as P0556, P0557, P0558, and P0559.
The function of the brake booster pressure sensor is to monitor the amount of engine vacuum that is available for the power brake booster.
Even though we troubleshoot this problem on a VW, Diagnostic Trouble Code (DTC) P0555 is a generic code and can come on in any make including Acura, Fiat, Alfa Romeo, Nissan, Ford, Dodge, Pontiac, Chevrolet, Acura, Subaru, Hyundai, Honda, Volvo, Mercedes-Benz, and other makes. The repair procedure will be similar, but the sensor location will vary.
The brake booster pressure sensor circuit detects the vacuum that is available for the power brake booster. The circuit is controlled by the Engine Control Unit (ECU), which uses the sensor to adapt braking power to various situations and adjust the available vacuum used to assist brake pedal operation.
- Brake light stays on or flashes.
- Check engine light stays on
- The brake pedal is difficult to press
- The vehicle takes longer to stop.
- Faulty brake booster sensor
- Cracked or damaged vacuum lines
- Corroded electrical connector
- Damaged wire harness to the sensor
- Faulty brake booster
- Faulty Engine Control Module (ECM)
- Replace faulty brake booster sensor
- Clean any corrosion built up at the sensor.
- Update, repair or flash ECU / ECM / PCM
- Replace damaged wires
- Replace damaged hoses
The vacuum generated by the engine is used by the power brakes to make slowing down the vehicle and applying the brakes much easier. If there is a problem with the brake system and no vacuum is being delivered to the brake booster, it may be much harder to apply enough pressure to the brakes.
Code P0555 usually is an electrical circuit fault, and brakes typically still function, but without diagnosing the problem, it may be difficult to know.