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On-board diagnostic (OBD) codes help mechanics and vehicle owners identify possible issues in a vehicle. But before you can troubleshoot and resolve these problems, it’s important to know what these codes mean.

Code P20EE is one of many trouble codes that may be logged and retrieved from the OBD system. Here is some basic information that may help you understand what getting this code may mean for your vehicle.

What Does the P20EE Code Mean?

Diagnostic trouble code (DTC) P20EE stands for “SCR NOx Catalyst Efficiency Below Threshold.” This code is logged when the powertrain control module (PCM) detects that catalyst efficiency is below the threshold on bank 1. Code P20EE refers to the selective catalytic reduction catalyst (SCR) on a diesel engine.

Diesel Exhaust Fluid (DEF) helps in converting harmful nitrogen oxides (NOx) into nitrogen (N2) carbon dioxide (CO2) and water. The DEF is injected into the SCR catalyst to perform the chemical reaction.

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Diesel Exhaust Fluid (DEF) helps in converting harmful nitrogen oxides (NOx) into nitrogen (N2) carbon dioxide (CO2) and water.

The powertrain control module (PCM) monitors the efficiency of the SCR catalyst using NOx sensors. If the SRC fails to efficiently perform its job, code P20EE will be logged.

Depending on the severity of the problem, related error codes may also be stored with this DTC. Code P20EE is very similar to error codes P20EC, P20ED, and P20EF.

Read our discussion about DEF to get more information that can help you address P20EE. Likewise, you can find more useful information in our in-depth discussion about EGR systems.

Note: The definition of code P20EE may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Possible Causes of the P20EE Code?

P20EE is a generic code, so it can have several triggers. Here are the most common:

What are the Common Symptoms of the P20EE Code?

You may notice the following symptoms if you drive a vehicle that has set a P20EE trouble code:

  • Active check engine light
  • Exhaust system warning messages on the dash
  • Derated engine performance
  • Poor fuel efficiency
  • DPF regeneration may not happen

How to Diagnose the P20EE Code

Error code P20EE is a generic code that may be set in different makes and models. However, this does not mean that there is a one-size-fits-all approach to diagnosing its underlying cause. The steps for troubleshooting this code will vary depending on your specific vehicle.

Check out the video below to get an idea of what the diagnostic process for this code might involve:

How to Fix the P20EE Code

Although code P20EE shares similar triggers and symptoms with other engine codes, the appropriate diagnostic and repair procedure will depend on the specifications of your vehicle. If you’re unfamiliar with auto repair, you should leave the job to a mechanic.

If you’re considering troubleshooting this code on your own, it’s a good idea to refresh your automotive knowledge before attempting any fixes. Always consult the vehicle repair manual or an online repair database to learn the appropriate diagnostic procedures for this code.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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