What does code P0556 mean?

Q: What does code P0556 mean?

Brake Booster Pressure Sensor Circuit Range/Performance. P0556 indicates that the powertrain control module (PCM) has detected an out-of-range or erratic signal from the brake booster pressure sensor, which monitors the vacuum or hydraulic pressure assisting your brakes. The PCM compares this signal to expected values under specific operating conditions and sets the code when the voltage or pressure reading falls outside the acceptable range or fails a rationality check.

DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P0556

P0556Brake Booster Pressure Sensor Circuit Range/Performance

P0556 indicates that the powertrain control module (PCM) has detected an out-of-range or erratic signal from the brake booster pressure sensor, which monitors the vacuum or hydraulic pressure assisting your brakes. The PCM compares this signal to expected values under specific operating conditions and sets the code when the voltage or pressure reading falls outside the acceptable range or fails a rationality check.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.