P0520: Engine Oil Pressure Sensor / Switch Circuit

Severity: high System: Engine Can drive: caution

Quick answer: P0520 means the engine oil pressure sensor or switch circuit is reading out of range or implausible. It is often just a faulty sensor or wiring — but because it can also indicate genuinely low oil pressure, you must check the oil level and confirm real pressure before assuming it’s only electrical. Genuinely low oil pressure can destroy the engine.

TL;DR

P0520 = oil pressure sensor/switch circuit fault. Severity: high. Most often a faulty sensor or wiring, but CHECK THE OIL and confirm real pressure first — genuine low pressure is critical. Top causes: bad sensor/switch (50%), wiring/connector (25%), low oil / real low pressure (25%).

Can I keep driving with P0520?

Caution — verify real pressure first.

IF the oil level is correct and a manual gauge shows normal pressure → it’s an electrical/sensor fault and you can drive while you fix it. IF the red oil pressure light is on, the oil is low, or a gauge shows low pressure → STOP; running with genuinely low oil pressure can destroy the engine.

Symptoms

Check engine light on
Oil pressure gauge reading wrong or erratic
Oil pressure warning light may be on
Usually no drivability change if it’s just the sensor
Possible oil leak from a failed sensor

Top causes (ranked by probability)

Likely cause	Probability	Notes
Faulty oil pressure sensor / switch	50%	Most common — but verify pressure first
Wiring or connector fault at the sensor	25%
Genuinely low oil pressure (low oil, pump, wear)	25%	Rule this out with a manual gauge

What does P0520 mean?

Technical explanation

The oil pressure sensor or switch reports engine oil pressure to the ECM/gauge. P0520 sets when its signal is out of range, stuck or implausible. The most common cause is a failed sensor/switch or its wiring/connector. However, the code can also be triggered by genuinely low oil pressure, so a mechanical oil-pressure test with a manual gauge is essential before condemning the sensor — driving with real low oil pressure can seize the engine.

In simple terms

A sensor measures your engine’s oil pressure. P0520 means that sensor’s reading doesn’t make sense. Usually the sensor or a wire is bad — but it could mean the oil pressure really is low, which is dangerous. So check the oil level and have the real pressure tested before assuming it’s just the sensor.

How to diagnose P0520 (step by step)

Check the engine oil level. Low oil can cause low pressure and trigger the code.
Test real oil pressure with a manual gauge. Critical step — confirm whether pressure is actually low before blaming the sensor.
Inspect the sensor and connector. Look for damage, oil contamination or a loose connector.
Check the wiring. Verify the signal and ground circuits to the sensor.
Replace the sensor if pressure is good. If mechanical pressure is normal, the sensor/wiring is the fault.

Repair options & cost

Replace the oil pressure sensor/switch
Repair the wiring/connector
Fix the cause of genuinely low oil pressure (oil, pump, etc.)

🔧 Doing it yourself? Buy the part: Oil pressure sensor

DIY cost	$15–$120
Workshop cost	$80–$350
Repair time	30–60 minutes (sensor)

Costs are local ballpark ranges and vary by region and vehicle.

Tools you’ll need

Scan your car: recommended OBD-II scanners →

Vehicle-specific notes

Always confirm real oil pressure with a mechanical gauge before assuming it’s just the sensor — this can save an engine.
The sensor is usually inexpensive and a straightforward DIY replacement.
A leaking oil pressure sensor can also cause oil loss — inspect for seepage.

Common mistakes to avoid

Replacing the sensor without verifying actual oil pressure first
Ignoring a red oil pressure light (real low pressure)
Overlooking an oil-contaminated connector
Driving on with genuinely low oil pressure

Frequently asked questions

Is P0520 dangerous?

It can be. Usually it’s a faulty sensor or wiring, but it can also indicate genuinely low oil pressure — which can destroy the engine. Always confirm real oil pressure with a manual gauge before assuming it’s only electrical.

Can I just replace the oil pressure sensor?

Often yes, if a manual gauge confirms the actual oil pressure is normal. If real pressure is low, replacing the sensor hides a dangerous problem — fix the pressure cause instead.

Should I drive with P0520?

Only after confirming the oil level is correct and real pressure is normal. If the red oil light is on or pressure is low, stop driving to avoid engine damage.

P0520 summary

Meaning	Oil pressure sensor/switch circuit fault
Severity	High
Safe to drive?	Caution — verify real pressure
Top cause	Faulty sensor/switch (50%)
DIY cost	$15–$120
Shop cost	$80–$350