What it means
The PS pressure sensor signal stays in electrical range but is implausible for the operating state, e.g. high pressure reported with the wheels straight.
At a glance
- Usually lights the check-engine light
How it works
The power steering pressure sensor tells the control module how steering pressure changes so it can compensate engine idle under load. P0551 sets when the signal is electrically plausible but does not match the steering or operating conditions, such as reporting pressure when the wheels are straight.
Common causes
Most likely first.
- Sensor drift or contamination
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
Symptoms
- Check-engine light on
- Idle may fluctuate during low-speed steering maneuvers
How to diagnose it
- Read freeze-frame data and compare the reported steering pressure with wheel position and engine speed at the time of the fault.
- Inspect the sensor mounting, connector, and nearby wiring for looseness, contamination, or damage that could distort the signal.
- With the wheels straight and then during a gentle steering input, monitor the pressure signal to see whether it responds consistently.
- Compare sensor output and circuit connections with the manufacturer's specification.
- Test the pressure sensor or switch for drift or an implausible response before replacing it.
Common fixes
- Secure a loose pressure sensor or switch and its connector.
- Clean contaminated terminals and repair damaged wiring.
- Correct a mounting or connection problem that is damping or distorting the signal.
- Replace a pressure sensor or switch that fails the specified response test.
Can I keep driving?
If steering and engine operation remain normal, cautious driving is generally possible, but idle may fluctuate during parking or other low-speed turns. Stop if the engine stalls or steering effort changes unexpectedly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.