What Is P20EE Code On Duramax: How To Fix?

Imagine yourself enjoying a peaceful drive. But suddenly, your dashboard lights up, showing some sort of P20EE code. Have you ever faced such situations? Do you know what to do in those times? Many of us don’t!

P20EE Code Duramax is a generic trouble code for automobiles. Whenever there’s a problem with the conversion of Nitrogen Oxide while the engine is running, it appears. Generally, it is due to the decreased efficiency of the catalysts below their threshold value.

But how do we fix it? Before knowing how to resolve the problem, it is necessary to know about the codes and what they imply. In today’s article, we will do a thorough discussion about them. Do you want to tag along? If yes, let’s begin our journey.

P20EE Code Duramax

What Does P20EE Code Mean On Duramax?

P20EE code Duramax is one of the diagnostic trouble codes (DTC) that can appear on your Onboard Diagnostic System (OBD) anytime. OBD system is a great help to both users and mechanics to identify what’s wrong with your car. Different codes refer to different types of malfunction.

If your OBD-ll ever shows P20EE code, understand that the SCR catalyst efficiency is below the minimum level it is supposed to be. The literal meaning of P20EE is SCR (Selective Catalytic Reduction) NOx (Nitrogen Oxides; NO, NO2, etc.) catalyst efficiency below a threshold level. Usually, it happens for one particular bank, normally bank-1.

SCR system in a car runs by injecting Diesel Exhaust Fluid (DEF) into the exhaust stream in front of the catalytic converter. DEF helps in converting poisonous NOx gases into harmless N2, CO2, and water. When the SCR fails to do its job correctly, code P20EE occurs.

What Are The Symptoms Of The P20EE Code On Duramax?

P20EE code refers to a particular malfunction on the Duramax diesel engine. So, obviously, it comes with a set of symptoms. You can predict P20EE with these signs even before appearing on the diagnostic board. Let’s get to know them.

  • Warning/ alert from the exhaust system
  • Excessive black smoke exhaustion
  • Reduction in fuel efficiency
  • Engine performance becomes low
  • Check engine light is active
  • PDF regeneration may not occur
  • Additional codes other than P20EE may also appear.

If you ever face these problems, check your car thoroughly for any malfunction, even though no code popped up.

The Causing Factors Of The Error P20EE Code

As P20EE code Duramax is one kind of generic code, several factors may trigger it. However, there are some common causes you will find almost 90% time. What are those? Find out below:

  • If the wires connecting the whole reductant injection system are damaged, burned, disconnected, or face short-circuits in any parts.
  • If the control circuit is damaged for any reason
  • For example, issues with control panel software, if software needs updates, can also lead to P20EE.
  • Defects in the reductant injection pump, dosing module, and injection nozzle can hinder injection on DEF.
  • If the exhaust gas temperature sensor/s, exhaust pressure sensor/s, NOx sensor/s, O2 sensor/s, and others are faulty
  • A low level of reductant or, more precisely, DEF is another reason for P20EE to appear.
  • If the reductant used in the system is contaminated or unsuitable or is not injected in an inaccurate amount, the whole reduction system will collapse.
  • Defective DEF heating system
  • Defects in SCR catalytic converter may fail SCR programming.
  • Check for any fluid leaks in the exhaust system.
  • Unauthorized, illegal, and improper modifications made by the user or mechanic in the exhaust system or engine system

Keep in mind that when the P20EE code appears, other related codes may also follow suit. So, the causation can be anything. You better be prepared all time.

How Serious Is Code P20EE On Duramax?

P20EE code won’t necessarily harm your car right away. But it is pretty serious if we consider the number of raw fuels like NOx dumped in the air. They are harmful to human health!

As there’s a low level of catalyst efficiency, the SCR system will fail gradually. It will lead to the exhaustion of harmful gases produced by the engine like NO and NO2 in the environment. So, yes, getting a P20EE code is quite severe.

How Do I Fix My Duramax P20EE Code?

As I have mentioned earlier, there can be many reasons for your car to show code P20EE. So, diagnosis of the valid reason is the key to fixing it. Depending on the cause, you may need to:

  • Replace the DEF if it’s not suitable for your car.
  • Measure correctly and use adequate DEF.
  • Replace faulty reductant injection parts.
  • Repair or Reprogram the Power train control module (PCM)
  • Replace the exhaust system
  • DEF heater replacement
  • Check all wirings for faulty connection.

Most users face trouble properly pinpointing where the problem lies. In that case, it is wise to go to a car mechanic. Isn’t it better to let professionals do their job?

How Much Does It Cost To Solve The Error Code?

If you are trying to fix the problem yourselves, the cost of solving this code would be a few hours. Time, dedication, and some parts if something needs to be replaced. It depends on what’s the reason for P20EE.

So, if you are fixing the code yourself, it would cost you the necessary labor. But if you depend on professionals for this job, it might cost you a few hundred. It varies depending on car models, defective parts, and where you live.

Common Mistakes When Diagnosing The P20EE Code

Finding the actual cause of P20EE can be very tricky. Even mechanics sometimes get confused if the problem lies within any control module. Thus, some mistakes are pretty common when diagnosing code P20EE.

  • Hard to detect of the control modules are faulty
  • The power train control module is defective
  • SCR system failure
  • Reductant control system

P20EE is good at deceiving. It will make you think the problem is with one part, while it’s actually in the opposite part. Leave it to professionals if possible.

people also ask (FAQs)

1. What causes the P20EE code?

Low, inaccurate, or contaminated Diesel Exhaust Fluid, defects in the reductant injection system, faulty wires, modules, etc., are the common causes of P20EE code flashing up.

2. What are Some troubleshooting Steps for code P20EE?

Reset all the additional code frames that come with P20EE. Hopefully, it will stop the codes from popping up. However, follow the car’s manual properly. Take help from a professional if needed.

3. Can I still drive with a P20EE code on board?

Yes, you can. Driving with P20EE is not an issue. But yes, there will be an emission of harmful gases into the air when you do that. The fuels can not convert to harmless ones due to a lack of reductants, which will lead to raw exhaustion.

4. What do you mean by reductant pressure too low?

It is an additional malfunction that comes with SCR failure. When the pressure in the reductant injection system between the pump and nozzle, code P20E8 pops up following P20EE.

Code P20EE Duramax, Failed NOx Sensor Diagnosis >> Check out the video below:

Final Verdict

Diagnostic trouble codes are like the language of automobiles. You will know what’s wrong with your car by understanding its meaning. It saves time and the hassles of trying to find the problem.

P20EE code Duramax is another trouble code notifying the lower efficiency of the catalytic converter. It can get quite serious if you don’t pay attention. In our article, we tried to give all the essential information we could think of regarding P20EE. Hopefully, it was helpful.

Getting to know the codes first is the primary step you should take to resolve them. Learn the codes with us, and have a smooth, enjoyable ride!

Who Worked on This post?



Anderson is an experienced auto mechanic with over 10 years in the industry. He is skilled in diagnosing and repairing a wide range of vehicles, from sedans to trucks and SUV

Syed Ahmed


Syed Ahmed has been working as an auto mechanic editor for the past five years. He has a background in mechanical engineering and a love for all things automotive

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