Dodge Ram P0521: Oil Pressure Sensor Switch → Performance/Range

P0521 This is an OBD2 diagnostic Code that is activated when you Dodge Ram 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 an oil system issue. It should be immediately diagnosed and repaired.  Although it's possible and likely that your oil pressure sensor/sensor is damaged, it may also mean there is an issue with your oil pressure.  

Your Ram’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 Dodge Ram



Índice de Contenido
  1. P0521 Quick Facts
  2. P0521 Symptoms:  Dodge Ram
  3. Ram P0521 Causes
  4. Diagnostics for Dodge Ram P0521
    1. 1. Examine the oil
    2. 2. Examine the Wiring Harness
    3. 3. Manually check your oil pressure
  5. Conclusion

P0521 Quick Facts

  • Most often caused by an issue with your Ram’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:  Dodge Ram

Below are some symptoms common to P0521.

  • 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.


Dodge Ram P0521 Diagnosis


Ram 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 Ram’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 some common reasons for P0521.

  • Low oil consumption or none The first thing that you should do is check to see if there is oil in your Ram’s engine at all.  It can also throw the P0521 error if it is very low or empty.  Clear the code and fill up the oil.  
  • Low oil pressure The code will appear if oil pressure drops too low.  This code should be able to be seen with an oil light or low oil pressure reading on the oil pressure gauge.  Diagnostics for Low Oil Pressure on Dodge Ram
  • 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. 
  • Wiring for Oil Pressure Sensor 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.


Diagnostics for Dodge Ram P0521

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

Check the oil level first.  If it’s full make sure that it looks healthy.  You may have an oil pressure sensor problem if the lid appears black or grimy.


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.  

One of the most common reasons this code is thrown is because there are wiring problems.  The wiring is close to the Ram’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 you use this 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.



It’s relatively straightforward diagnosing P0521.  It's much easier to know the oil pressure.  Leave a comment below to share your thoughts and best wishes with the Dodge Ram.

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