P0520: Engine Oil Pressure Sensor/Switch Circuit Malfunction

P0520 means the ECU sees an out-of-range or implausible signal on the oil pressure sensor circuit. Usually a failed sensor or wiring fault, but it can also flag genuinely low oil pressure, which is why you can't just clear it and drive.

P0520 is a electrical-related diagnostic trouble code classified as high severity. When your vehicle's ECU detects this condition, it stores P0520 and illuminates the check engine light.

If your vehicle has triggered P0520, you may notice one or more of these symptoms:

• Check Engine light on, often paired with the red oil pressure warning
• Oil pressure gauge reads zero, pegged high, or jumps erratically
• Low oil pressure warning chime at idle
• Reduced-power or limp mode on GM trucks and some BMWs
• Ticking or lifter noise if pressure is actually low
• Oil weeping from the sensor body onto the block

Here are the most common causes of P0520, ranked by how likely they are to be the culprit:

No - address this immediately. The ECU can't tell if you have real oil pressure or not. If the pressure actually is low and the sensor is dead, you can wipe bearings in minutes. Check the dipstick and confirm pressure with a mechanical gauge before driving.

Follow these steps to pinpoint the root cause of P0520:

1. Check oil level on the dipstick (or via the electronic gauge on BMW/Audi) before anything else. If it's low, top up and inspect for leaks.
2. Connect a mechanical oil pressure gauge at the sensor port. Compare idle and 2500 rpm readings to the service manual spec (typically 25-30 psi hot idle, 55-65 psi at 2500 rpm on most engines).
3. If real pressure is in spec, unplug the sensor connector and inspect for oil intrusion, green corrosion, or spread pins.
4. Key on, engine off: back-probe the connector. Confirm 5V reference (variable sensors) or battery voltage (switches), a clean ground, and continuity on the signal wire back to the PCM.
5. Substitute a known-good sensor, clear the code, and retest under the conditions that set it.
6. If the code returns with a good sensor and clean wiring, scope the signal for dropouts during a road test.
7. If actual pressure is low, drop the pan and inspect the pickup screen for sludge before condemning the pump.

Repair costs for P0520 vary depending on the root cause and your vehicle. Here are typical estimates:

P0520 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:

These codes are often seen alongside P0520 or indicate related issues: