P0555
Brake Booster Pressure Sensor Circuit
Brakes
Generic OBD-II
High
What it means
P0555 means the ECM has detected a fault in the brake booster pressure sensor circuit — the sensor that reports vacuum or pressure inside the brake booster. Your brakes still function through the mechanical booster, but the code can disable features that rely on the sensor (like stop-start or hill-hold) and, because it's a brake-system fault, it should be diagnosed promptly.
High
Can I keep driving? Your brakes still work through the mechanical booster, but this is a brake-system fault — get it diagnosed promptly and brake with extra care.
Common symptoms
What you'll notice
- Check-engine light on
- Brake or ABS warning light may illuminate
- Auto stop-start, hill-hold, or driver-assist features may be disabled
- Brake pedal feel may change on vehicles that use the sensor for boost control
Common causes
Most likely first
- Faulty brake booster pressure sensorLikely
- Open or short in the sensor signal, power, or ground wiringCommon
- Corroded or loose sensor connectorCommon
- Less commonly, a faulty ECM or brake control moduleLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data to see the conditions when it set.
- Inspect the booster pressure sensor connector and wiring for damage or corrosion.
- Check the sensor's vacuum/pressure supply line for leaks or blockage.
- Test the sensor signal against spec and replace it if faulty.
- Repair any wiring faults, then clear the code and re-test.
FAQ
Quick answers
Is it safe to drive with P0555?+
The mechanical brake booster still provides assist, so you can stop the car, but because it's a brake-related fault you should have it checked promptly and drive cautiously.
Can I just clear P0555?+
It will come back until the sensor or wiring is repaired. Clearing it also hides any real brake-system issue, so fix the cause first.
Related codes
Often seen with P0555
Read & clear P0555 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX