P0550Power Steering Pressure Sensor/Switch Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Hydraulic power steering has a pressure switch or sensor on the high-pressure line; when the wheel is turned at standstill, pump pressure and engine load rise sharply, so the engine module raises idle air in advance to stop the engine stalling. That makes it an input to idle control under CARB. Switches (Saab, Mitsubishi) ground a pull-up; analogue 5 V sensors (Toyota) give about 0.45 V at zero pressure. GM's and Ford's tables do not use P0550–P0554. P0550 is the general circuit fault. No manufacturer document available to us uses it. Without the signal the engine can drop or stall at full lock, or the module raises idle permanently as a substitute.
- What you may notice
- Check engine light (depending on the maker)
- Idle drops when steering at standstill, engine may stall
- Raised idle (substitute value)
- Likely causes
- LikelyConnector or wire open or corroded (splash zone at the pump)
- LikelySensor or switch faulty, often also leaking
- Possible5 V reference or ground disturbed
- RareEngine module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.