Power Steering Pressure Sensor Circuit Range/Performance
The P0551 code indicates that the Power Steering Pressure (PSP) sensor circuit is out of the expected range or performance. The PSP sensor monitors hydraulic pressure in the power steering system and sends a signal to the Engine Control Module (ECM). When the ECM detects a voltage signal that is too high, too low, or not changing as expected, it sets this code. This can affect steering assist and engine idle speed control.
1. Most Common Causes
- Faulty power steering pressure (PSP) sensor
- Open, short to ground, or short to power in the sensor circuit wiring or connectors
- Low power steering fluid level or air in the system
- Defective power steering pump or internal leaks
- Internal PCM failure (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Hard or heavy steering, especially at low speeds
- Erratic or surging idle when turning the steering wheel
- Loss of power steering assist
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Inspect power steering fluid level and condition; top off or replace if necessary.
Step 3: Visually check the PSP sensor wiring and connector for damage, corrosion, or loose connections.
Step 4: Test the PSP sensor signal voltage with a multimeter; compare to manufacturer specifications.
Step 5: If sensor and wiring are okay, test the power steering pump pressure and check for system blockages.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause loss of power steering assist, making the vehicle difficult to steer, especially at low speeds. Additionally, it may affect engine idle and increase the risk of an accident.
How much does it cost to fix?▼
The cost to fix P0551 typically ranges from $50 to $150 for diagnosis and sensor replacement. If wiring repairs or power steering pump replacement is needed, costs can be higher.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.