P0556: Brake Booster Pressure Sensor Circuit Range/Performance
What does P0556 mean?
P0556 is a diagnostic trouble code indicating "Brake Booster Pressure Sensor Circuit Range/Performance". The sensor or component is providing readings, but they fall outside the expected operating range. The part may be degraded, contaminated, or experiencing intermittent issues affecting turbo/supercharger performance.
Symptoms you may notice
- Check engine light (MIL) illuminated on dashboard
- ABS warning light on
- Brake pedal feels different
- Unusual braking behaviour
- Intermittent warning lights
Estimated repair cost
Typical range in Australia (parts + labour)
Common causes
- Worn or contaminated turbo/supercharger component
- Vacuum leak or intake air leak
- Clogged filter or restricted flow
- Intermittent electrical connection issue
What should you do?
This code sits in the braking system. Your normal hydraulic brakes generally still work, but the electronics layered on top of them, ABS, EBD and emergency brake assist, can drop out. You will not notice until you brake hard or brake on a wet or loose surface, and that is the moment they would have helped. Treat the car as needing a workshop rather than as safe to drive, and get it looked at before your next real trip.
Get a diagnosis for YOUR car
Code P0556 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.