What Does P0520 Mean?
The engine oil pressure sensor or switch circuit has a general malfunction. The ECM is unable to obtain a valid oil pressure reading due to an electrical issue in the sensor circuit. The oil pressure warning light on the dashboard may illuminate or behave erratically. This code does not necessarily mean oil pressure is actually low, but the ECM cannot confirm it is adequate.
Safety Warning
STOP AND VERIFY. Until you confirm oil pressure is actually adequate with a mechanical gauge, treat this as a potential low oil pressure condition. Driving with genuinely low oil pressure will cause catastrophic engine damage within minutes. If the oil pressure warning light is on and you cannot verify pressure, do not drive the vehicle.
Common Causes
40%
Faulty oil pressure sensor/switch
25%
Damaged or corroded wiring/connector at the oil pressure sensor
20%
Open or short in the oil pressure sensor circuit
10%
Oil contamination or sludge physically damaging the sensor
5%
ECM internal circuit fault on oil pressure input
Diagnostic Steps
1
Check live data for the oil pressure sensor PID. At warm idle, expect 15-30 PSI on most engines; at 2500 RPM expect 30-60 PSI. An implausible fixed value (0 PSI or max scale) confirms a sensor/circuit fault.
2
Inspect the oil pressure sensor connector for oil contamination (common — the sensor often weeps oil), corrosion, or a loose connection. Clean with electrical contact cleaner.
3
Measure sensor supply voltage and ground at the connector with KOEO. Verify the reference voltage (5V for 3-wire sensors) and check ground continuity (<0.5 Ohm to engine ground).
4
Install a mechanical oil pressure gauge in the sensor port to verify actual oil pressure. This confirms whether the issue is electrical (sensor/circuit) or mechanical (oil pump/bearings). Compare readings: warm idle >10 PSI, 2500 RPM >25 PSI.
5
If mechanical pressure is normal, replace the oil pressure sensor. Use an OEM or quality replacement — aftermarket sensors in this location are a common cause of repeat failures.
Estimated Repair Cost
$50 - $300
Parts + labor, varies by vehicle and location
The engine oil pressure sensor or switch circuit has a general malfunction. The ECM is unable to obtain a valid oil pressure reading due to an electrical issue in the sensor circuit. The oil pressure warning light on the dashboard may illuminate or behave erratically. This code does not necessarily ...
The most common cause of P0520 (Engine Oil Pressure Sensor/Switch Circuit Malfunction) is: Faulty oil pressure sensor/switch
Typical repair costs for P0520 range from $50 to $300, depending on the vehicle, location, and whether you do it yourself or go to a shop.
STOP AND VERIFY. Until you confirm oil pressure is actually adequate with a mechanical gauge, treat this as a potential low oil pressure condition. Driving with genuinely low oil pressure will cause catastrophic engine damage within minutes. If the oil pressure warning light is on and you cannot verify pressure, do not drive the vehicle.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0520 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Lubrication System
Difficulty
Type
Generic (SAE)
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