Chevy Silverado P0521: Oil Pressure Sensor Switch → Performance/Range

P0521 An OBD2 diagnostic code is generated when the vehicle is detected as having an OBD2 fault. Chevy Silverado The sensor detected that the value sent by the oil pressure sensor was outside of the normal operating range.

A bad oil pressure sensor, or an issue in the oil system can cause this problem. This should be addressed immediately.  It is possible, and even probable that an oil pressure sensor/sensor is defective. However, it could also indicate a problem in the oil pressure.  

Your Silverado’s oil pressure sensor measures the oil pressure mechanically, and converts that reading into a voltage signal that the PCM (Powertrain Control Module) converts into an oil pressure reading.  This is the reading that you will see on your Oil Pressure Gauge and activates the Oil Warning Light.

P0521 Quick facts

• Most often caused by an issue with your Silverado’s oil pressure sensor or circuit
• Take P0521 seriously
• Most common symptoms are the oil light and an incorrect oil pressure gauge reading.
• It is easy to diagnose

P0521 Symptoms:  Chevy Silverado

Below are the top symptoms of P0521.

• Low oil light/Gauge Although P0521 can often be caused by an oil pressure sensor problem, it is important to treat readings from your oil gauge or low oil warning as if they were correct.
• Ticking, Knocking, and Other Things If your engine is ticking and knocking, it’s likely that the oil pressure sensor is accurate and there’s a problem with the engine or you need oil.
• Check Engine Light– That’s why you are here.

Silverado P0521 Causes

The problem with your sensor wire or sensor sensor is what causes P0521. This would indicate that your engine is in good condition.  Or it is going to be caused by an issue your Silverado’s oil level, viscosity, pressure, or cleanliness.  

This code is important because it ensures proper oil flow.

Below are the top causes of P0521.

• You can have low or no oil The first thing that you should do is check to see if there is oil in your Silverado’s engine at all.  The crankcase can give you P0521 if it is not full or very low in oil.  This can be fixed by filling the oil with more, clearing the code and resetting the crankcase.  
• Low Oil Pressure This code may appear if the oil pressure is too low.  The code will be visible with an oil light and/or a low reading on the oil pressure gauge.  Chevy Silverado Low Oil Pressure Diagnosis
• Wrong oil or dirt? If there hasn’t been an oil change for a long enough period of time, it can interfere with the oil pressure sensor, even if there still is oil pressure. 
• Oil Pressure Sensor Wiring - P0521 means that the signal coming from the oil pressure sensors is not within the range.  It indicates that the wiring is not working properly.
• Oil Pressure Sensor It is possible that the problem may be caused by an oil pressure sensor. However, it's smart to first look at the oil and wiring.

P0521 Diagnosis: Chevy Silverado

This P0521 diagnosis order is written (like everything on the site) for the DIY guy who doesn’t have a lot of specialty tools. 

1. Take a look at the Oil

Check the oil level first.  If it’s full make sure that it looks healthy.  You may have an oil pressure sensor problem if the lid appears blackened or grimy.

2. Examine the Wiring Harness

Next, you should inspect the wiring harness running from the oil pressure sensor to the PCM.  You could have P0521 if the wiring is damaged.  Don’t forget to make sure that the harness is still plugged into the sending unit and undamaged.  

One of the most common reasons this code is thrown is because wiring problems are very common.  The wiring is close to the Silverado’s exhaust and can get brittle over time.

3. You can manually check the oil pressure

After confirming that both the wire and the oil level are good, it is time to check the oil pressure manually.  There are two options: Manual oil pressure gauge to see if it’s where it needs to be.  They're easy to use.  Here’s a Great YouTube Video This will demonstrate how you can use the gauge to test.

If the oil pressure from the gauge reads ok, you’ll need to replace the oil pressure sending unit/sensor.  They’re cheap.  If there is low or no oil pressure, you’ll need to figure out why.

Conclusion

It’s relatively straightforward diagnosing P0521.  It's much easier to know the oil pressure.  Leave a comment below to share your thoughts and best wishes with the Chevy Silverado.