Power Steering Pressure Sensor Circuit Malfunction
Your car's power steering pressure sensor is sending a bad signal to the engine computer, like a broken gauge at a gas station. The steering system may not work correctly because the computer can't read the pressure properly.
The ECU monitors voltage output from the power steering pressure sensor to verify hydraulic system pressure is within safe operating range. It detects open circuits, short circuits, or out-of-range voltage signals that indicate sensor failure or wiring issues.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor Voltage Output | 0.5–4.5 volts proportional to pressure | Below 0.1V or above 4.9V, or fixed voltage |
| Pressure Reading | 50–200 PSI at idle to load conditions | Implausibly high or impossibly low reading |
Code P0551 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0551 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.