P0550 Power Steering Pressure Sensor Circuit Malfunction

P0550 indicates a malfunction in the power steering pressure sensor circuit. The controller cannot trust steering load information used for idle and engine load compensation.

Code details

Generic OBD-II · P0

System: Speed / Idle
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not adjust idle strategy or replace idle parts before checking power steering pressure feedback.

Symptoms of P0550

Unstable, high, or low idle, or stalling.
Erratic speedometer, cruise-control, or shift behaviour.
Check-engine light with a hesitation or surge.

Common causes of P0550

A dirty throttle body, idle-control valve, or throttle-position sensor.
A failing vehicle-speed or wheel-speed sensor, or its wiring.
Vacuum leaks or a related sensor forcing the idle/speed strategy.

Useful checks before replacing parts

Compare power steering pressure sensor data, steering angle or effort, idle speed, engine load, freeze-frame conditions, and related idle control codes.
Inspect sensor reference voltage, ground, signal wire, connector condition, fluid leaks, pump load, belt condition, and harness routing near steering components.
Turn the steering under controlled conditions and confirm the pressure signal changes smoothly with load.

Related OBD-II codes

These nearby speed / idle entries can help compare wording and pin down the fault area.