P0520: Engine Oil Pressure Sensor or Switch A Circuit

What it means

Engine Oil Pressure Sensor or Switch A Circuit: an electrical fault is present in the circuit.

At a glance

• Usually lights the check-engine light

How it works

Oil pressure sensor or switch A reports engine oil pressure to the control module, which monitors its electrical circuit. P0520 sets when that circuit has an electrical fault, such as an open, short, or loss of power or ground. The code alone does not establish whether actual oil pressure is low.

Common causes

Most likely first.

1. Faulty oil pressure sensor or switch
2. Open or shorted wiring in the sensor circuit
3. Loose, corroded, or damaged connector
4. Blown fuse or loss of power or ground

Symptoms

• Check-engine light on
• Oil-pressure warning light may illuminate
• Oil-pressure gauge may read abnormally or not respond

How to diagnose it

1. Check the scan tool for freeze-frame data and related oil-pressure codes, and note whether the oil-pressure warning light is on.
2. Check the engine oil level and look for obvious leaks before running the engine further.
3. Inspect oil pressure sensor or switch A’s connector and wiring for looseness, corrosion, or damage.
4. Test the sensor circuit for opens and shorts, then verify its power and ground against the manufacturer’s specification.
5. If the circuit checks pass but readings remain abnormal, verify actual oil pressure using the manufacturer’s diagnostic procedure.

Common fixes

• Secure or repair a loose, corroded, or damaged sensor A connector.
• Repair an open or short in the oil-pressure sensor circuit.
• Restore a failed fuse, power feed, or ground after identifying its cause.
• Replace oil pressure sensor or switch A if it fails circuit testing.

Can I keep driving?

If the oil-pressure warning light is on, the gauge reads abnormally, or the engine makes unusual noise, stop the engine and do not continue driving until actual oil pressure is checked. Low oil pressure can quickly damage the engine.