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

P0521 This is an OBD2 diagnostic Code that is activated when you Chevy Impala detects that oil pressure sensor value is not within its normal range.

It's usually due to a problem with your oil system or a bad oil pressure sensor. 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 Impala’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.  The oil warning light is activated when this reading appears on the Impala's oil pressure gauge.

P0521 Quick facts

• Most often caused by an issue with your Impala’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 Impala

These are some of the symptoms that P0521 is most commonly associated with:

• 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 or Knocking - 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.

Impala P0521 Causes

Problems with sensor wiring or the sensor are what will cause P0521. Your engine should be fine.  Or it is going to be caused by an issue your Impala’s oil level, viscosity, pressure, or cleanliness.  

Proper oil flow is vital to an engine's performance. This code must be respected and followed.

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 Impala’s engine at all.  The crankcase can give you P0521 if the oil level is very low.  This can be fixed by filling the oil with more, clearing the code and resetting the crankcase.  
• Low Oil Pressure The code will appear if oil pressure drops too low.  The code will be visible with an oil light on the engine or the low reading of the oil pressure gauge.  Chevy Impala 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 The signal from an oil pressure sensor has gone out of range. P0521 is the result.  It indicates that the wiring is not working properly.
• Oil Pressure Sensor Although the P0521 problem is most likely caused by the oil pressure sensor, it is worth looking into the wiring and oil first.

P0521 Diagnosis: Chevy Impala

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. Examine the oil

First, check your oil level.  If it’s full make sure that it looks healthy.  It may interfere with your oil pressure sensor if it is blackened or gritty.

2. Examine the Wiring Harness

Next, you should inspect the wiring harness running from the oil pressure sensor to the PCM.  It could also be the cause of P0521.  Don’t forget to make sure that the harness is still plugged into the sending unit and undamaged.  

This code can be thrown for many reasons, including wiring issues.  The wiring is close to the Impala’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.  These are simple to use.  Here’s a Amazing 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 is much easier to know the oil pressure.  If you have any suggestions, please leave them below. Good luck with your Chevy Impala.