Power Steering Pressure Sensor/Switch Range/Performance
What does P0551 mean?
The P0551 code means the vehicle's onboard diagnostic system has detected: Power Steering Pressure Sensor/Switch Range/Performance. This is a low severity code.
Common Symptoms
- Engine idle fluctuates when turning steering wheel
- Occasional stalling during parking maneuvers
- Idle speed compensation not matching steering load
- Power steering feels inconsistent
- Check engine light on
Probable Causes (Ranked by Likelihood)
- PSP sensor giving inaccurate or out-of-range readings Very High
- Intermittent connection at PSP sensor connector High
- Power steering system issue affecting pressure readings Moderate
- Air in power steering system causing pressure fluctuations Moderate
- Worn power steering pump producing inconsistent pressure Low
Step-by-Step Diagnostic Procedure
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Monitor PSP sensor reading with scan tool while turning wheel -- should change smoothly with steering input
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Compare PSP reading at rest versus full lock -- should show clear pressure increase
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Check power steering fluid for air bubbles (foamy fluid indicates air in system)
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Bleed power steering system by turning wheel lock to lock 10-15 times with engine running
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Replace PSP sensor if readings are erratic or do not correlate with steering input
Frequently Asked Questions
Can I drive with code P0551?
Yes, you can drive. The engine may occasionally stumble or stall during parking maneuvers. Be prepared to feather the gas pedal when turning the wheel at low speeds to prevent stalling.
What does range/performance mean for the PSP sensor?
It means the PCM is receiving readings from the PSP sensor that do not match expected values for current driving conditions. The sensor may be reading pressure that does not correlate with steering wheel position or engine load.
Can air in the power steering system cause this code?
Yes. Air in the hydraulic power steering system causes pressure fluctuations and foamy fluid, which can produce erratic PSP sensor readings. Bleed the system by turning the wheel lock to lock multiple times with the engine running and the fluid reservoir cap off.