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Engine mechanicalSeverity High: diagnose before driving on

P0520Engine Oil Pressure Sensor/Switch "A" Circuit

What it means

The ECU has detected an electrical fault in the oil pressure sensor circuit: the signal is missing, stuck or outside the range the sensor can produce. The oil pressure sensor measures the engine oil pressure.

Symptoms

  • Oil pressure warning light
  • Possibly engine noise (ticking or knocking)
  • Reduced power on some engines

Common causes

  • Open or shorted signal, 5 V reference or ground wire
  • Corroded, loose or water-filled connector
  • Failed oil pressure sensor
  • Fault on the shared 5 V reference (another sensor pulling it down)

What to check first

  1. With the key on, measure the 5 V reference and the ground at the sensor connector
  2. Back-probe the signal and compare it with live data while wiggling the harness
  3. Check for other codes on the same 5 V reference (e.g. P0641, P0651)
Can I drive with P0520? Not recommended. P0520 can lead to stalling, limp mode or engine damage; diagnose it before driving further.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

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P0520: questions and answers

What does P0520 mean?

P0520: Engine Oil Pressure Sensor/Switch "A" Circuit. The ECU has detected an electrical fault in the oil pressure sensor circuit: the signal is missing, stuck or outside the range the sensor can produce. The oil pressure sensor measures the engine oil pressure.

What are the symptoms of P0520?

Oil pressure warning light. Possibly engine noise (ticking or knocking). Reduced power on some engines.

What causes P0520?

Open or shorted signal, 5 V reference or ground wire. Corroded, loose or water-filled connector. Failed oil pressure sensor. Fault on the shared 5 V reference (another sensor pulling it down).

How do you diagnose P0520?

1. With the key on, measure the 5 V reference and the ground at the sensor connector 2. Back-probe the signal and compare it with live data while wiggling the harness 3. Check for other codes on the same 5 V reference (e.g. P0641, P0651)

Can I drive with P0520?

Not recommended. P0520 can lead to stalling, limp mode or engine damage; diagnose it before driving further.