P0521 – Meaning, Causes, Symptoms, & Fixes

Code P0521 Definition

Engine Oil Pressure Sensor/Switch Range/Performance

What Does P0521 Mean?

The oil pressure sensor calculates the oil pressure of the vehicle’s engine. This is then communicated to the ECM in the form of a voltage value. The P0521 code is set when the ECM detects the voltage value is either higher or lower than the specified acceptable range of oil pressure. This code can also be set when the engine detects constant fluctuation of the oil pressure value.

What Are the Symptoms of Code P0521?

  • Check engine light
  • Oil pressure warning light
  • Oil pressure gauge too high/low
  • Engine stall

What Is the Cause of Code P0521?

  • Low engine oil level
  • Faulty oil pressure sensor
  • Disconnected wiring in oil pressure circuit
  • Disconnected wiring in EGR circuit
  • Engine failure

How Serious Is Code P0521? – Severe

Initially, this trouble code will not prevent your vehicle from regular operation. However, if not addressed early on, this code can cause serious internal damage to your engine causing complete engine failure. It is recommended to take your vehicle to the nearest dealership to have this code properly repaired to avoid costly repair(s).

Code P0521 Common Diagnosis Mistakes

Prematurely replacing the oil pressure sensor without visually inspecting the wiring of the oil pressure circuit for disconnection.

Tools Needed to Diagnose:

How to Diagnose and Repair Code P0521:

  1. Check to see if there are any other codes along with P0521 and clear your Check Engine Light with FIXD.
  2. Check the freeze frame data in an attempt to pinpoint the issue.
  3. Use the dipstick to check the oil level of your vehicle is sufficient.
  4. Verify the oil filter and drain plug are secure with no leakage.
  5. Visually inspect the wiring around the oil pressure sensor for disconnection.
  6. Check voltage of oil pressure sensor to ensure it is within specified range.
  7. If the problem persists, consider replacing the oil pressure sensor.

Was this post helpful?

Comments 15

Chester Parson

November 26, 2018

oil level was low. raised oil level to proper amount .erased code .SEEMS TO BE OK NOW.


May 1, 2020

What was the final thought. I have been having the same problem. Light came back on. The dealer changed the oil pump, sensor, screen and oil change. Was good for 1 year. 1 year and 1 month after the warranty expired. Light Popped back up. I changed the sensor myself this time. Light went away and came back up again. Oil level is good.

Jimy Fink

May 17, 2020

I’m having the exact same problems!

Evertt Hurtado

September 14, 2020

Did your issue go away?


September 26, 2020

This code has made its ugly appearance whilst using my FIXD scan tool on my svz but my check powertrain warning is displayed on the dash computer next to my engine light can anyone confirm that the code and computer warning on dash are in direct relation to each other or am I looking at two different issues?

Troy Nissen

November 3, 2020

Check your gascaps! You might just be surprised!!

Max Clubb

January 14, 2019

Took my car to my mechanic after using my FIXD to diagnose the check engine light which appeared very suddenly on my car. After FIXD showed a code of P0521, I took my vehicle to my mechanic. His sophisticated system showed the same code and the oil pressure pressure switch was replaced. Very happy that I purchased the FIXD and also purchased some for other members of my family. Thanks for an excellent product.

FIXD Marketing

January 14, 2019

That’s awesome Max! So glad we could help!


Darrell Simmons

February 14, 2019

I like fixd has been on point every time great to have

Oliver Nichols

March 18, 2019

Ran the synthetic oil passed the oil life mileage. Oil pressure reading about 20-25 psi. Changed oil and filter and oil pressure reading 40-50 psi. Removed code and has not come back.

Terry W Adams

May 7, 2019

Took my car to dealer. They replaced switch. Continued my trip. Stopped for gas and check engine light came back on as I accelerated to enter highway.

David Rickard

May 20, 2019

FIXD has been a big help to me as I do work on my Trail Blazer myself . Some were a pain but I adhered to fixing the problems at hand, a great product !

Timothy C Domer Sr

November 26, 2019

I have FIXD and had this error code pop up earlier this year on my GMC Sierra. I took it to the dealer and they ran diagnostics on it and came up with the same error. They replaced the sensor and did an oil/filter change. Nine months later I get the same error message again. It seems strange that the sensor went “bad” again so soon. Looks like I’m going back to the dealership again.


February 21, 2020

Just had my oil pressure sensor changed out including the filter that goes in there too light turned off and just came back on oil level is good what else could be the problem? 2013 Chevy Silverado 1500


April 27, 2020

I’m having same problem now what did yours end up being


October 23, 2020

Did you ever come up with anything? I have the same problem.


June 5, 2020

I have a 2013 GMC with same problem

Julian Gutierrez

July 21, 2020

Hi, Check engine light on my dash, replaced the oil pressure sensor along with the small filter on my 2012 Tahoe. The check engine light disappeared after replacing the sensor but after driving couple of miles it came back up again, I deleted it and after couple of days showed up again and never went away. Any suggestions please thank you…


October 23, 2020

Did you ever come up with anything? I brought it to the dealer. They charged me $500. It’s back on. They wanna do $1200 more of exploratory work with no idea if it will work I’m so frustrated.

Troy Nissen

November 3, 2020

Check your gas cap! You might be surprised!

en English