Power Steering Pressure Sensor/Switch Circuit
What does P0550 mean?
The P0550 code means the vehicle's onboard diagnostic system has detected: Power Steering Pressure Sensor/Switch Circuit. This is a low severity code.
Common Symptoms
- Engine idle drops when steering wheel is turned
- Engine stalls when parking or turning at low speed
- Hard steering at idle
- Idle speed does not increase during steering maneuvers
- Check engine light on
Probable Causes (Ranked by Likelihood)
- Faulty power steering pressure (PSP) sensor/switch Very High
- Damaged or corroded PSP sensor wiring or connector High
- Low power steering fluid level Moderate
- Power steering pump failure causing abnormal pressure Moderate
- PCM input circuit failure Low
Step-by-Step Diagnostic Procedure
-
Check power steering fluid level and condition -- top off if low
-
Monitor PSP sensor signal with a scan tool while turning the steering wheel lock to lock
-
Inspect PSP sensor connector for corrosion, fluid contamination, or loose pins
-
Measure PSP sensor voltage -- should change when steering wheel is turned (typically 0.5V to 4.5V range)
-
Check for 5V reference voltage and good ground at the sensor connector
Frequently Asked Questions
Can I drive with code P0550?
Yes, you can drive safely. The main issue is that the engine may stall when you turn the steering wheel at low speeds or during parking. The PCM uses the PSP signal to raise idle speed during steering loads, so without it, the engine may lug down.
What does the power steering pressure sensor do?
The PSP sensor tells the PCM when the power steering system is under load (when you turn the wheel). The PCM then increases idle speed to compensate for the extra load on the engine from the power steering pump, preventing stalling.
Do electric power steering vehicles have this sensor?
No. Vehicles with electric power steering (EPS) do not have a hydraulic power steering pump or PSP sensor. This code applies only to vehicles with traditional hydraulic power steering systems. Most newer vehicles (2012+) use electric power steering.