Chevy Malibu 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 Malibu The oil pressure sensor detects an error and sends a message to inform the user that it is outside its normal operating range.

Problems with your oil system or the oil pressure sensor are most common causes. 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 Malibu’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 Malibu's oil gauge. It also triggers an oil warning light.

P0521 Quick Facts

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

P0521 Symptoms:  Chevy Malibu

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

• Glow-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 Tipping 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.

Malibu 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 Malibu’s oil level, viscosity, pressure, or cleanliness.  

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

These are some of the leading causes for P0521.

• Low oil consumption or none The first thing that you should do is check to see if there is oil in your Malibu’s engine at all.  The crankcase can give you P0521 if the oil level is very low.  Clear the code and fill up the oil.  
• 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.  Chevrolet Malibu 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 The signal from an oil pressure sensor has gone out of range. P0521 is the result.  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.

P0521 Diagnosis: Chevy Malibu

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.  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 Malibu’s exhaust and can get brittle over time.

3. Manually check your oil pressure

After confirming that both the wire and the oil level are good, it is time to check the oil pressure manually.  A Oil pressure can be manually adjusted gauge to see if it’s where it needs to be.  They're easy to use.  Here’s a Great YouTube Video That will explain exactly how you use the gauge for checking.

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.  Leave a comment below to share your thoughts and best wishes with the Chevy Malibu.