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

P0521 An OBD2 diagnostic code is generated when the vehicle is detected as having an OBD2. Chevy Equinox 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.  Although it's possible and likely that your oil pressure sender/sensor may be defective, it is also possible to have an issue with your oil pressure.  

Your Equinox’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 oil pressure gauge.

P0521 Quick Facts

• Most often caused by an issue with your Equinox’s oil pressure sensor or circuit
• Take P0521 seriously
• A common sign is an oil light, or an inaccurate reading on the oil pressure gauge.
• Simple to diagnose

P0521 Symptoms:  Chevy Equinox

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

• Low oil light/Gauge The most common cause of P0521 is a poor oil pressure sensor. However, the readings from an oil pressure gauge or low-oil warning should be treated as correct until you are certain.
• Ticking and 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.

Equinox P0521 Causes

Problems with sensor or wiring can cause P0521. Your engine should be fine.  Or it is going to be caused by an issue your Equinox’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 Equinox’s engine at all.  It can also throw P0521 if the crankcase is low or empty.  Clear the code and fill up the oil.  
• Oil pressure is low 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.  Chevrolet Equinox Low Oil Pressure Diagnosis
• Wrong or dirty oil- 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.  This is a signal that there are wiring problems.
• 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.

Diagnose: Chevy Equinox

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. Check 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.  

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

3. You can manually check the oil pressure

If the wiring and oil levels are in good condition, you can manually test the oil pressure.  A 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 is much easier to know the oil pressure.  If you have any suggestions, please leave them below. Good luck with your Chevy Equinox.