P0520: Engine oil pressure sensor/switch circuit malfunction
The engine computer gets a missing, implausible or out-of-range signal from the oil pressure sensor or switch, so it can’t be sure the oil pressure is right. The pressure may really be low.
Updated
What P0520 means
Oil pressure keeps a film of oil between the engine’s moving parts. A sensor or a switch on the engine reports it, to the engine computer and to the red oil pressure warning on the dashboard.
P0520 means the circuit of that sensor or switch has a fault: the engine computer gets no signal, or one that can’t be right. It may well be the sensor, but neither the computer nor you can tell a broken sensor from a really low pressure without measuring it.
P0521 to P0523: range, low and high
P0521 means the reading doesn’t make sense, for example it fluctuates or doesn’t match what the engine computer expects; P0522 that it’s too low, and P0523 too high. P0522 in particular can be a real low pressure. The advice is the same for all of them: check the oil level, and have the pressure measured.
P0521: Engine Oil Pressure Sensor/Switch A Range/Performance
P0522: Engine Oil Pressure Sensor/Switch A Low
P0523: Engine Oil Pressure Sensor/Switch A High
Can I keep driving?
Drive gently
Check the oil level before driving on. If the red oil pressure warning is on or flickers, the oil level is low, or the engine ticks or knocks, don’t drive: switch the engine off and have it recovered. Otherwise drive gently, only as far as you need to, and have the oil pressure measured soon. Until then, treat the warning as real.
General guidance based on the code alone, not on the car’s actual condition. If in doubt, stop and ask a mechanic.
A real low oil pressure can damage the engine within minutes. If the red oil pressure warning comes on while driving, stop when it’s safe to do so and switch the engine off.
With a faulty sensor, the red warning may also fail to come on when the pressure really drops. That’s why the pressure should be measured soon.
Symptoms
- The red oil pressure warning flickers or stays on.
- An oil pressure gauge, on cars that have one, reads erratically or not at all.
- If the pressure is really low: ticking or knocking from the engine.
Common causes
- Faulty oil pressure sensor or switch. Sensors and switches can fail with heat and age. Replace one only after the pressure has been measured.
- Wiring or connector fault. The sensor sits on the engine, where its connector is exposed to heat and oil.
- Low oil level, or a real low oil pressure. From a low level, a worn oil pump or engine wear. Rule this out first, with a mechanical gauge.
Typical fixes
- Switch the engine off on level ground, wait a few minutes and check the oil level. If it’s low, top up with the oil specified for your car and look for leaks.
- If the red oil warning stays on or flickers, or the engine ticks or knocks, don’t drive on: have the car recovered.
- Have the oil pressure measured with a mechanical gauge fitted in place of the sensor.
- If the pressure is fine, check the sensor’s connector and wiring, then replace the sensor or switch.
- If the pressure is low, have the oil pump, its pick-up and the engine checked, as for P0524.
Questions
Can I drive with P0520?
Only after checking the oil level, and then only gently and as far as you need to until the oil pressure has been measured. If the red oil pressure warning is on or flickers, the level is low, or the engine ticks or knocks, don’t drive: switch the engine off and have it recovered.
Is P0520 just a bad sensor?
Often it is, but the code can’t tell. Only a measurement with a mechanical gauge shows whether the pressure is really low. Until then, treat the warning as real.
What is the difference between P0520 and P0524?
P0520 to P0523 mean the sensor’s signal is faulty or implausible. P0524 means the engine computer reads a real low oil pressure: stop when it’s safe to do so and switch the engine off.