P0520 Code Meaning and Next Steps

First checks take 10 to 15 minutes for the first checks. No special tools are usually needed for the first checks.

Can you keep driving?

Stop driving if any of these apply

!The engine starts running much worse, stalls, or the warning light flashes.
!There is a leak, a strong odor, or a loss of control-system function that makes the vehicle unsafe to keep driving.

If the light is steady and the vehicle still drives normally: Often yes for a short time, but it should not be ignored.

What to check first

Step-by-step checks

1
Safety first
If the engine is noisy, rattling, or the oil light is on steadily, shut it down before inspecting anything else
2
Free - no tools
Check the oil level and condition before assuming the sensor is at fault
3
Basic tool needed
Inspect the connector and harness near the oil sender for leaks, damage, or corrosion
4
Basic tool needed
If possible, compare the dash warning with a mechanical oil-pressure test before replacing parts
5
Basic tool needed
If the code appeared after an oil change or repair, verify the connector was plugged back in properly

If the code returns

-If oil pressure is actually good and the signal is still wrong, the sensor or switch becomes more likely.
-If the code returns after a connector repair, check the wiring under heat and vibration.
-If the engine really has low oil pressure, treat that as the primary fault and do not chase the code alone.

Background

What this code means

P0520 is a generic OBD-II the engine oil pressure sensor or switch circuit code.

This code can come from the sensor, wiring, connector, or the oil-pressure switch itself rather than an actual low-oil-pressure event.

The oil warning light may flicker, or the code may appear even when the engine sounds normal.

Diagnosis

Common causes

Most common

Faulty oil pressure sensor or switch

The sender can fail even if oil pressure is normal.

Common

Connector or wiring issue

A bad connection can make the circuit look wrong.

Common

Low oil level or real pressure issue

A true lubrication problem can trigger the code.

Possible

Oil contamination in the connector

Oil intrusion can affect the signal path.

Avoid these mistakes

What not to do

xDo not replace sensors first if there is an obvious wiring, connector, vacuum, or fluid issue.
xDo not ignore drivability changes just because the code sounds like a control-circuit problem.

Parts

Parts that may need replacing

PartTypical costNotes

Oil pressure sensor or switch$20-$120Relevant when the circuit is the fault rather than oil pressure itself.

Connector pigtail repair$15-$90Worth checking if the connector is oil-soaked or damaged.

Oil change or pressure test$50-$150Useful to confirm the basic lubrication side first.

Related OBD codes

P0521

P0521 usually means the engine oil pressure reading is out of normal range or performance.

P0522

P0522 usually means the engine oil pressure sensor circuit is reading too low.

P0523

P0523 usually means the engine oil pressure sensor circuit is reading too high.

Source notes

Generic OBD-II (SAE J1979 / ISO 15031-5). P0520 was expanded around common oil pressure sender circuit faults, including sensor failure, wiring issues, and real oil-pressure concerns.

This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.

This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.

Last reviewed: 2026-04-10

Reference: Open reference

P0520 - P0520 Usually Means the Engine Oil Pressure Sensor or Switch Circuit Is Not Behaving Correctly