P0520: Engine Oil Pressure Sensor/Switch "A" Circuit
The oil pressure sensor or switch circuit has a fault.
High risk
Check the oil level immediately. If the red oil light comes on, stop the engine.
Short answer · Can I keep driving with P0520?
Only after checking the oil level. If the level is correct and the red oil light stays off, drive gently to a workshop. If the red light comes on, stop the engine.
What does P0520 mean?
Code P0520 means the engine control unit sees an electrical fault in the oil pressure sensor or switch circuit. The code alone does not mean the oil pressure is low, but the engine is now less protected.
A leaking sensor or oil in the connector are common causes.
What the car does when the code is set
The check engine light comes on and, depending on the car, the oil pressure warning may be shown or may no longer work correctly. Some engines with a variable oil pump switch to maximum pressure as a precaution.
How the system works
Engine oil is pumped through the bearings and other moving parts under pressure. The pressure rises with engine speed and falls as the oil gets hot and thin. A switch or sensor in the oil gallery reports this pressure. A switch only says whether there is enough pressure, while a sensor gives a continuous reading the engine control unit can use, for example to control a variable oil pump. If the electrical signal is out of range or does not fit the engine speed and temperature, a code is stored.
Common symptoms
Possible causes
Listed without ranking. The cause on your car depends on make, engine and mileage — see the maker notes below.
- Low oil levelAlways check this first.
- Faulty oil pressure sensor or switchA common cause, often with an oil leak at the sender.
- Wiring or connector faultOil in the connector or a damaged wire.
- Real low oil pressureA worn oil pump, blocked pickup or worn bearings.
How it is diagnosed
- Check the oil level nowPark on level ground and check the dipstick or the oil level display. Top up with the specified oil if needed.
- Confirm the pressure mechanicallyA workshop fits a mechanical gauge in place of the sensor to measure the real oil pressure.
- Check the connector and wiringLook for oil in the connector and damaged wiring.
- Replace the sensor if the pressure is rightIf the measured pressure is within specification, the sensor or wiring is at fault.If the red oil pressure light is on, stop the engine. Running without oil pressure destroys the engine in minutes.
Questions about P0520
Is this code a sensor problem or real low pressure?
The code alone cannot tell. Only a mechanical pressure test confirms whether the engine has enough oil pressure.
How do I know the oil pressure is really fine?
Only a mechanical gauge test confirms it. The red oil pressure light is a warning; a sensor code is not.