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  • DTC P0520 stands for “Engine Oil Pressure Sensor/Switch “A” Circuit.”
  • This is logged when the PCM detects problems with the oil pressure sensor, oil pressure switch, or the oil pressure in general.
  • Code P0520 is usually triggered because of faulty oil pressure sensors, bad circuitry, and low oil pressure.
  • Some of the most common symptoms associated with this code include a lit check engine light, a malfunctioning engine, and the vehicle being stuck in “limp mode.”

If your scan tool or code reader is showing the P0520 code, this guide will provide its definition, causes, and symptoms.

What Does Code P0520 Mean?

The P0520 engine code is set when the reading from the oil pressure sensor differs from the manufacturer’s specification. Oil pressure is essential to maintain the longevity of every internal combustion engine.

Having the correct oil pressure ensures that there’s a cushion of oil between the rotating internal engine components. The car’s computer or powertrain control module (PCM) monitors the oil pressure by sending a reference voltage to the engine oil pressure sensor. This sensor returns voltage output to the PCM, which is analyzed and compared to the ideal oil pressure programmed in it.

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The PCM monitors the oil pressure by sending a reference voltage to the engine oil pressure sensor.

Inside the oil pressure switch is a pressure-sensing device that’s in direct contact with the oil flow. Oil pressure can either increase or decrease the sensor’s resistance and the PCM is capable of converting these changes into an accurate interpretation of the actual oil pressure.

In other words, the oil pressure sensor that triggers a P0520 code is typically a three-wire sensor with 5 volts, a signal return ground, and a signal voltage that varies with engine oil pressure. The sensor’s job is to convert engine oil pressure to a voltage reading that the ECM/PCM is programmed to interpret as an accurate indicator of engine oil pressure.

The oil pressure sensor that triggers a P0520 code is typically a three-wire sensor with 5 volts, a signal return ground, and a signal voltage that varies with engine oil pressure.

– Richard McCuistian, ASE Certified Master Automobile Technician

A working pressure sensor will output a voltage within an upper and lower voltage limit. The lower threshold is purposely greater than 0V so that a circuit check can be performed on the device. If the PCM determines the sensor voltage is outside the ideal threshold for a period of time, the sensor’s signal is deemed invalid and code P0520 is set.

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Read our note about oil pressure for different OEMs before you attempt any DIY troubleshooting for code P0520.

Note: The definition of code P0502 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Possible Causes of the P0520 Code?

Knowing the possible origin of the problem helps in troubleshooting any trouble code. It is important to know what’s causing the P0520 code before taking action. Make sure to take note of these probable causes:

What are the Common Symptoms of Code P0520?

Be keen in observing any changes in your vehicle. There could be multiple symptoms for code P0520. Here are the common ones you need to watch for:

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One common symptom of error code P0520 is an illuminated check engine light.

How to Diagnose the P0520 Code

There are different ways of diagnosing the OBD code P0520 as it has several possible causes. Don’t expect a universal diagnosis as vehicles are built differently depending on the make and model. It’s a viable option to consult a certified mechanic to avoid inconveniences that may lead to expensive repairs.

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How to Fix the P0520 Code

It is possible that the P0520 code in your car requires a different fix than the one you’ve read online. Components in a car may be laid out differently depending on the car manufacturer and this makes it impossible for someone to come up with a universal solution. In addition, there are different designs of oil pressure switches, making a repair or replacement tricky.

To help you with the diagnosis, you can get an ALLDATA single-vehicle subscription, which you can use to help clear code P0520. This subscription will not only help you clear this specific code, it can also help you clear other ones that may be set in the future.

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About The Authors
Written By Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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