OBD2 Car ScannerWhat does P0556 mean?
P0556 stands for Brake Booster Pressure Sensor Circuit Range/Performance. The engine computer has found a problem with vehicle speed signals, idle control or another sensor input.
Powertrain codes cover the engine, transmission and emissions. When the car's computer sees a reading outside its normal range, it stores this code and may turn on a warning light on the dashboard.
Common causes
- Faulty vehicle speed sensor
- Dirty throttle body or idle air control valve
- Faulty switch or sensor
- Damaged wiring or connector
What to do
- Read all stored and pending codes with a scanner. Several codes together often point to one cause.
- Note the freeze frame data (speed, temperature, load) recorded when the code was set.
- Inspect the wiring and connectors of the part named in the code for damage, corrosion or looseness.
- Fix the most likely and cheapest cause first, then clear the code and drive to see if it comes back.
Read this code from your own car
Plug in a cheap ELM327 adapter and the app shows every fault code, what it means and how to fix it.
Frequently asked questions
What does P0556 mean?
P0556 means “Brake Booster Pressure Sensor Circuit Range/Performance”. It belongs to the speed, idle control and inputs group: The engine computer has found a problem with vehicle speed signals, idle control or another sensor input.
Is it safe to drive with P0556?
You can usually drive carefully for a short time, but fix it soon to avoid further damage or higher fuel use.
How do I clear P0556?
Fix the cause, then clear the code with an OBD2 scanner or app. If the fault is still there, the code will come back.
Related codes
- P0552Power Steering Pressure Sensor Circuit Low Input
- P0553Power Steering Pressure Sensor Circuit High Input
- P0554Power Steering Pressure Sensor Circuit Intermittent
- P0555Brake Booster Pressure Sensor Circuit
- P0557Brake Booster Pressure Sensor Circuit Low
- P0558Brake Booster Pressure Sensor Circuit High
- P0559Brake Booster Pressure Sensor Circuit Intermittent
- P0560System Voltage Malfunction
Code meanings can vary by manufacturer. This page is general guidance, not a repair manual. Always confirm the cause before replacing parts.