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

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

This is usually caused by an oil pressure sensor problem or an oil system issue. It should be immediately diagnosed and repaired.  Although it's possible and likely that your oil pressure sender/sensor may be defective, it's also possible to have an issue with your oil pressure.  

Your Suburban’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 Suburban's oil pressure gauge.

P0521 Quick facts

• Most often caused by an issue with your Suburban’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.
• Simple to diagnose

P0521 Symptoms:  Chevy Suburban

Below are the top symptoms of P0521.

• 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 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.

Suburban Causes P0521

Problems with sensor or wiring can cause P0521. Your engine should be fine.  Or it is going to be caused by an issue your Suburban’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.

• No oil or low-quality The first thing that you should do is check to see if there is oil in your Suburban’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 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.  Diagnostics for low oil pressure in Chevy Suburban
• 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 oil pressure sensor signal is not in 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.

P0521 Diagnosis: Chevy Suburban

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.  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.  

This code can be thrown for many reasons, including wiring issues.  The wiring is close to the Suburban’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.  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 That will explain exactly how to 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 fixing your Chevy Suburban.