P0550: Power Steering Pressure Sensor/Switch Circuit
What to do
Driveable, with normal steering. You may notice the idle dipping or the engine stalling when manoeuvring at full lock, which is the characteristic symptom and is worth reporting as such.
What this code means
A circuit fault on the power steering pressure sensor. The engine module reads steering pressure for one reason: hydraulic power steering places a substantial load on the engine at low speed, and parking with the wheel at full lock can be enough to stall an engine at idle. Knowing that the steering is loaded lets the module raise idle speed slightly to absorb it.
So the symptom of losing that signal is not a steering complaint at all — it is an idle that dips or stalls when parking. That mismatch between the code's name and the symptom is what makes it worth explaining.
Likely causes
Start here
- Faulty power steering pressure sensor · moderate
- Corroded or loose connector · easy
Less common
- Damaged wiring harness near exhaust heat · moderate
- Low power steering fluid level · easy
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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