Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P0555 Brake Booster Pressure Sensor Circuit

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modeNo

The brake booster pressure sensor (5 V reference, signal, ground) measures the vacuum in the brake booster. On direct-injection, turbo, stop-start and hybrid engines intake vacuum is scarce, so the engine module watches it and creates vacuum when needed – closing the throttle, suppressing engine stop or running an electric vacuum pump. That makes it an input to idle and throttle control. P0555 is the general circuit fault without low/high distinction. No manufacturer document available to us uses it; GM splits circuit faults into P0557 and P0558. The module then assumes a substitute value and keeps vacuum available as a precaution.

Likely causes

Connector or wire to the sensor open or corroded
Sensor faulty
5 V reference disturbed (short at another sensor on the same reference)
Engine module

Symptoms

  • Check engine light or brake booster warning
  • Stop-start inactive
  • Often no change in driving

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–250
Time0.5–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

brake booster pressure sensorsensor wiringengine control module

Related codes

P0556P0557P0558P0559P0641

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com.