What Does P20E8 Code On Powerstroke mean? [Issues + Fixes]

A lot of our vehicles have a special system that works to control emissions. It involves an advanced injector that ensures fewer toxins by adding special fluids. In case it doesn’t hit the right pressure, we get an illuminated Check Engine Light. And that shows P20E8 Code On Powerstroke as the problem. 

So in short, P20E8 is set when reductant injection pump fails to insert DEFs into exhaust stream at a specific pressure of 51PSI. 

This may make us wonder why we get such a trouble code. Can I fix the code myself? Well, I’ll say, you can if the issue is simple. But it can also be serious. But don’t worry, I have got solutions to all of them. 

What Is P20E8 Code On Powerstroke?

P20E8 is a diagnostic trouble code that signifies “Reductant Pressure Too Low”. We get this code when vehicle computer senses a shortage of pressure in the reductant injector. 

To understand why it happens, I think you should know the whole scenario here from the beginning. 

Lots of byproducts are formed during combustion, and one of them is Nitrogen Oxide (NOx). Although “Exhaust Gas Recirculation” (EGR) valve helps reduce NOx, it results in lower engine power. That’s when Selective Catalytic Reduction (SCR) comes into play. 

What’s An SCR?

It’s an aftertreatment system that works without affecting performance. It converts NOx into something less harmful like nitrogen, water vapor, and a few carbon dioxides. Studies consider it a dominating technology to treat these emissions by reducing them by up to 90% or more. 

The method starts with an advanced injector that inserts reductants like Diesel Exhaust Fluids (mostly urea solution or ammonia) into the exhaust stream. It then goes into a catalyst-converting unit where NOx reacts with DEF. And consequently, the mix gets transformed into nitrogen and water molecules. 

What Does Reductant Have To Do With PCM?

The reducing agent has to be injected into the chamber at a super-specific pressure and in an accurately metered amount to work. Precisely, the pressure must reach 51PSI within 45 seconds of pumping. Why? Because it helps supply DEFs evenly throughout the converter. 

To make sure this happens, our vehicle uses an injection pump that’s controlled by Powertrain control module (PCM). The computer continually monitors both the level and temperature of DEFs present in a special storage tank. 

So, when there’s any problem in the injection system where it can’t insert DEFs at a specific pressure, PCM deduces it as a lack of pressure. And thus, the computer throws P20E8 code on Powerstroke and illuminates the Check Engine Light. 

quick Troubleshooting guide for P20E8 Code On Powerstroke

Here are some of the issues that make PCM set P20E8 erroor code on Powerstroke and ways to deal with them. 

When the problem is just low reductant pressure, there might be 6 causes that trigger P20E8 code. Each of them has an individual P20E8 fix. 

1. Loose Or Broken Connections

Sometimes loose or broken connections in the line pressure set a P20E8 code. They also may get corroded, burnt, kinked, damaged, or shorted. Most of the time, issues related to connectors occur over time. 

In case it’s loose, fasten the connections securely. If you find them completely damaged, I recommend you get new ones. Also, check if Reductant Control Module harness is shorted or open. Then, have it repaired or replaced accordingly. 

2. Faulty Or Dried Reductant Injector Pump Or Nozzle

Several reasons can cause damage to reductant injector pump, filter, and/or nozzle. Two of them are corrosion and contamination. When rust and dirt overpower the system, it causes abrasion and leakage that fail the components. Consequently, it can’t inject DEFs at the required pressure making computer give you a P20E8 error code. 

The only solution is to have the part replaced whichever is bad. But before that, I suggest you conduct a leak test at least 3 times using a scanner to verify it. Because the pressure might get lower when the pump filter dries out too.  

You can resolve it by re-saturating the filter. Just allow the pump to sit in reductant overnight. Then, do a leak test again and see if the pump is able to build pressure. If it does, then solved. 

In case it doesn’t, then check which is bad. 

If pump is the culprit, change it. When you buy a new one, make sure to prime it.

3. Damaged Reductant Purge Valve

PCM commands the reductant purge valve to open so that the reductant pressure equalizes in the DEF tank. However, the valve can malfunction mostly due to corrosion and harsh environmental conditions. These issues lead the computer to primarily set a P0443 code. But, you may get a P20E8 alert too. 

In that case, change the reductant purge valve. 

4. Unstable Reductant Pressure Sensor

The reductant pressure sensor works to monitor and control the quantity of fluids the pump puts out. It may become unstable due to short circuit that results in DEF inconsistency. Not just that, damage to the sensor because of faulty connections to the sensor or debris on it can cause the same trouble. And both can lead to P20E8 in Powerstroke. 

Use multimeter to check the voltage and see if there’s any circuit issue. Repair accordingly. In case it malfunctions, then get a new sensor. 

5. Low-quality Reductants

Using low-quality reductants can affect the system. Similarly, the quality of reductants can get lower due to crystalized deposits, contamination, DEF dilution, and low temperature. When too much urea fluids are present in the tank or too much water is in the DEF, it affects the quality and efficiency. This may cause the injector system to fail and make PCM throw a DTC P20E8.

So, in case the alert is just because the reductants aren’t good, then fill the tank with fresh and high-quality ones. Also, I think it’ll be more effective if you clean the crystalized deposits from the pump. 

6. Leakage

Any damage to the injector nozzle or pressure feed line can result in such error code. It may happen over time, due to extreme pressure, or corrosion. 

So, check the parts for any leakage. Fix or replace them in case it’s completely damaged. 

How To Clear P20E8 Code On Powerstroke?

The following steps work to clear P20E8 Code On your Powerstroke. It helped not only me but many too who suffered. 

1. Re-saturate the pump filter if it dried out. 
2. Change the faulty reductant injection pump or nozzle. 
3. Prime the reductant injection pump with clean DEF. 
4. Tighten, repair, and replace the pressure line connections. 
5. Use fresh and high-quality reductants. 
6. Restore or replace the bad reductant purge valve.
7. Get a new Reductant Pressure Sensor if damaged. 

How Much Does It Cost To Repair P20E8 Code?

Depending on the problem, the cost to repair P20E8 Code may range from a few dollars to over $5,000. 

It can be free if you just saturate the dried pump filter overnight. In case it doesn’t solve, then bad pump might be one of the problems. 

And DEF pump replacement may cost around $2,300 while filter parts may take around $3,000 or more. 

Frequently Asked Questions (FAQs)

in conclusion P20E8 Code On Powerstroke

While the fault of reductant injection system is a major cause of such trouble code, a failing PCM can be one too. Particularly, if its link to the sensor or pump is affected, it may “think” that the pressure isn’t sufficient and illuminate CEL by sending the code. So, make sure to check the entire system before taking any steps. 

This way, you can spot the problem specifically and fix it efficiently whenever you’re struck with P20E8 – reductant pressure too Low. 

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Iyul Nasruddin

Nasruddin is a passionate car enthusiast with a love for troubleshooting and diagnosing all sorts of vehicle problems. With years of experience in OBD diagnostics, Nasruddin, has become an expert in identifying and solving complex automotive issues.