P0555
Brake Booster Pressure Sensor Circuit
A general circuit fault is detected on the brake booster pressure sensor - the ECU cannot determine vacuum reserve in the booster, which limits the safe operation of stop-start, regenerative-braking blending, and electric vacuum pump control.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: easy
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Common causes
Ordered by how often each turns out to be the cause.
- Open in sensor or wiringCommon
Parts involved
- Brake Booster Pressure Sensor
P0555 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.