Engine Oil Pressure Sensor/Switch Circuit Malfunction
The P0520 code indicates a malfunction in the engine oil pressure sensor or its circuit. The Powertrain Control Module (PCM) detects that the signal from the oil pressure sensor is out of the expected range or missing. This can be due to a faulty sensor, wiring issues, low oil level, or mechanical oil pressure problems. The sensor is typically a switch that closes when oil pressure is above a threshold, or a variable sensor that provides a voltage signal proportional to pressure.
1. Most Common Causes
- Faulty or worn engine oil pressure sensor
- Damaged, corroded, or deteriorated sensor wiring insulation
- Loose, corroded, or bent pins in the sensor connector
- Short to ground in the sensor signal circuit
- Short to power in the sensor signal circuit
- Open circuit in the sensor wiring
- Excessive resistance in circuit connections
- Internal ECM/PCM failure (less common)
- Actual oil pressure out of range affecting sensor reading (in applications with variable-type sensor)
2. Symptoms You Will Notice
- Illuminated Check Engine Light
- Oil pressure warning light on dashboard
- Engine noise or knocking from low oil pressure
- Engine may run rough or stall
3. Step-by-Step Diagnosis
Step 1: Check engine oil level and condition; top off or change if necessary.
Step 2: Inspect the oil pressure sensor connector and wiring for damage, corrosion, or loose connections.
Step 3: Use a multimeter to test the sensor signal circuit and reference voltage (typically 5V).
Step 4: Test the oil pressure sensor itself by measuring resistance or voltage output with engine running.
Step 5: If sensor and wiring are good, check actual oil pressure with a mechanical gauge to rule out engine mechanical issues.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Low oil pressure can cause severe engine damage. Have it diagnosed immediately.
How much does it cost to fix?▼
Typically $50-$150 for parts and labor, but can be higher if wiring repairs or oil pressure issues are involved.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.