Engine

P0520 — Engine Oil Pressure Sensor/Switch Circuit Malfunction

Severity: high Drive with care, to a shop

What P0520 means

The engine control module detected a signal from the oil pressure sensor or switch circuit that is out of range or does not match engine operating conditions. The cause can be a bad sensor or wiring, but it can also be truly low oil pressure. Confirming actual pressure comes first.

Symptoms

  • Oil pressure warning light on
  • Check engine light on
  • Oil pressure gauge reads zero or fluctuates
  • Ticking or knocking if pressure is truly low
  • Warning light flickers at idle

Possible causes

  1. Failed oil pressure sensor or switch
  2. Damaged, corroded or chafed wiring and connector
  3. Actually low oil pressure from a worn pump or bearings
  4. Low oil level or fuel-diluted oil
  5. Wrong oil viscosity
  6. Clogged oil pickup or oil filter
  7. Rarely, a faulty engine control module

How to diagnose

  1. Check the oil level and condition on the dipstick, noting viscosity and any fuel smell
  2. Scan for codes and save the freeze frame data
  3. Measure real oil pressure with a mechanical gauge
  4. Inspect the sensor for oil leaks and the connector and harness for damage or corrosion
  5. Check supply voltage, signal and ground at the sensor connector
  6. Test the sensor against the manufacturer's specifications
  7. Check the wire to the module for opens and shorts
  8. If pressure and wiring are fine, test the control module

Common fixes

  • Top off or change the oil and filter with the specified grade
  • Replace the oil pressure sensor or switch
  • Repair the wiring harness or connector
  • Fix the cause of real low pressure, such as the pump, pickup or engine wear

P0520 on different brands

Ford · manuals
On Ford, P0520:01 identifies the engine oil pressure sensor "A" circuit in the 2024-2025 gasoline-engine monitor strategy and reflects the condition the monitor detected, not a confirmed failed part.

Questions and answers

Can I drive with a P0520 code?

Check the oil level and actual pressure first. If the red oil light is on or the engine knocks, shut it off right away to avoid serious damage.

Does P0520 always mean a bad sensor?

No. It points to a circuit problem, which could be wiring, low oil or genuinely low pressure. Replace the sensor only after a mechanical gauge test.

Can the wrong oil cause P0520?

Yes. Oil that is too thin or diluted with fuel can lower pressure, especially when hot. Use the viscosity listed in your owner's manual.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.