P0521 OBD-II Trouble Code: Engine Oil Pressure Sensor/Switch Range/Performance

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Cost of diagnosing the P0521 code

P0521 is a diagnostic trouble code (DTC) for "Engine Oil Pressure Sensor/Switch Range/Performance". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

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P0521 OBD-II Trouble Code: Engine Oil Pressure Sensor/Switch Range/Performance

Diagnostic Trouble Code (DTC): P0521

P0521 code definition

The P0521 code is defined as there being a fault with the engine oil pressure sensor/switch range/performance.

What the P0521 code means

Every modern vehicle is outfitted with a PCM (Powertrain Control Module). This computer controls a number of sensors, controls and other electronic components. One such sensor is the oil pressure sensor which detects how much mechanical oil pressure is present in the engine. It then sends this reading to the PCM in the form of a voltage value.

The PCM will then notify the driver of this information one of two ways. In some vehicles, there is a gauge in the dashboard that will show how much oil pressure there is. In other models, there is no gauge, but a warning light will be activated if there is a problem where oil pressure is concerned.

If the PCM ever detects an unexpected value, the P0521 code is stored. The unexpected value could simply be more or less than the acceptable range or the pressure could simply be fixed in place when it should be fluctuating.

What causes the P0521 code?

Some common causes behind the P0521 code are:

  • An open or shorted wiring in the oil pressure sending unit circuit
  • Mechanical engine failure
  • A faulty oil pressure

That being said, the most common cause for this trouble code is a lack of sufficient engine maintenance on the part of the owner. Not getting regular oil changes can eventually result in a low oil pressure/level condition. The majority of engines go through at least a quart of oil every 3,000 miles. At that point, it needs more.

What are the symptoms of the P0521 code?

As we mentioned above, this problem is usually accompanied by a dashboard alert in one of two ways. The mechanic working on the car may also notice related codes have been stored. These would be:

  • P0520
  • P0522
  • P0523
  • P0524

If the oil in the vehicle gets too low, but the driver doesn’t know because they aren’t given an accurate reading. Another symptom could simply be loud noises coming from the engine. Allowed to continue, engine failure could result.

How does a mechanic diagnose the P0521 code?

Diagnosing the P0521 will begin with the mechanic using an OBD-II scanner to extract all the codes the PCM has stored. If the dashboard warning light is on, that will also help the technician with their diagnosis.

To confirm what the vehicle’s reporting mechanisms are saying, the mechanic will pop the hood and check the oil levels. If the oil seems fine, they’ll clear the PCM of its codes and restart the vehicle to see if they return. Should they do so, the PCM is to blame.

Common mistakes when diagnosing the P0521 code

The oil pressure sensor may need to be replaced, but a mechanic shouldn’t do so until they carry out a full inspection. While this may actually clear the code and make the dashboard light go away, the engine could have already been damaged. By not inspecting this, the mechanic will send their customer back on the road with a huge problem under the hood.

How serious is the P0521 code?

If caught early and immediately addressed, this code doesn’t have to worry anyone. That being said, if the driver tries putting it off for a while, serious engine damage could be done. At the very least, it will cost a lot to fix. The worst case scenario is complete engine failure which is a very expensive problem to have.

What repairs can fix the P0521 code?

A lot of times, all it takes is changing out the oil and/or resetting the oil pressure sensor. The engine itself may require some serious repairs.

Additional comments for consideration regarding the P0521 code

This should be a good reminder to owners that their vehicle needs oil changes every 3,000 miles. Putting it off may not seem like a big deal, but it could quickly become one.

Need help with a P0521 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

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Related questions

Bad oil pressure sensor

A common failure in your vehicle is the oil pressure sending unit. Once the sensor is replaced, these codes should go away. I would ask for help from one of the mechanics at YourMechanic to replace your oil pressure sensor...

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