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

P0521 This is an OBD2 diagnostic Code that is activated when you Chevy Tahoe The oil pressure sensor detects an error and sends a message to inform the user that it is outside its normal operating range.

This is usually caused by an oil pressure sensor problem or other issues with your oil system. It should be immediately diagnosed and repaired.  Although it's possible and likely that your oil pressure sensor/sensor is damaged, there may also be an issue with the oil.  

Your Tahoe’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.

Quick Facts P0521

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

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, 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.

Tahoe 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 Tahoe’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 Tahoe’s engine at all.  It can also throw P0521 if the crankcase is low or empty.  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.  This code should be accompanied by the oil light or low oil pressure readings from the gauge.  Chevy Tahoe 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. 
• Wiring for Oil Pressure Sensor 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 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 Tahoe

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. Check 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 common.  The wiring is close to the Tahoe’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.  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.  This is made easier by knowing the exact oil pressure.  Leave a comment below to share your thoughts and best wishes with the Chevy Tahoe.