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P0555 Generic (SAE) Basic entry

Brake Booster Pressure Sensor Circuit

Updated 2026-10-02 · Vehicle speed, idle control & auxiliary inputs

Severity
Medium
Typical repair cost
60 – 500 EUR
System
Powertrain

What it means

P0555 is defined as "Brake Booster Pressure Sensor Circuit". the engine control module stores it when the monitored condition for this component or system is outside the limits programmed by the manufacturer.

This entry is compiled automatically from the standard definition and typical diagnostic practice for this type of fault. A detailed, reviewed article is in preparation.

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Symptoms

  • Check engine light on
  • Idle too high, too low or hunting
  • Stalling when coming to a stop
  • Speedometer or cruise control not working in some cases

Common causes

  1. Brake Booster Pressure Sensor Circuit worn, contaminated or out of calibration
  2. Mechanical problem in the system the sensor measures
  3. Air, vacuum or exhaust leak influencing the reading
  4. Wrong or low-quality replacement part
  5. Wiring resistance causing a small voltage offset

How to diagnose

  1. Compare the live Brake Booster Pressure Sensor Circuit reading with a known-good value or a second sensor at idle and at 2500 rpm
  2. Check for air, vacuum or exhaust leaks that could skew the reading
  3. Inspect the component for contamination and clean it if the design allows
  4. Verify the part number is correct for the engine
  5. Replace the Brake Booster Pressure Sensor Circuit if the reading remains out of specification

Frequently asked questions

Can I keep driving with P0555?

Usually yes for a short time, but expect reduced performance or higher fuel use. Have it diagnosed within a few days.

Will clearing P0555 fix it?

No. Clearing only erases the stored code; it returns as soon as the monitor runs again unless the cause is repaired.

Related codes

P0553P0554P0556P0557

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