What Is P20B9 Code 6.7 Powerstroke – 3 Ways To Fix

Trucks are one of the coolest vehicles you can own. They look great and they can easily handle heavy-duty tasks. Unfortunately, they require a lot of maintenance. You’ll quickly realize this if you ever encounter a P20B9 Code 6.7 Powerstroke.

P20B9 is a DTC that indicates Reductant Heater “A” Control Circuit/Open. This issue means there is something with one of three components: the DEF tank, the DEF heater, or the PCM. You need to replace these parts instantly either yourself or through a mechanic.

I understand that this issue can be quite confusing for a novice car enthusiast. Even well-versed ones struggle to understand this code. Don’t worry though, I’ve got your back with everything you need to know about P20B9

What Is P20B9 Code 6.7 Powerstroke – 3 Ways To Fix

P20B9 Code 6.7 Powerstroke – what does it mean?

P20B9 is a diagnostics trouble code (DTC) which means “Reductant Heater ‘A’ Control Circuit/Open”. DTCs are codes received by the OBD scanners that tell you what is wrong with your vehicle. What exactly does this one mean for your Ford 6.7L Powerstroke?

Reductant Heater A is the heater in your DEF tank. It keeps the DEF from freezing when it gets cold. P20B9 means that the engine’s brain PCM has not picked up any voltage from this heater. Hence, there must be an issue.

3 most common reasons Of The Error Code P20B9

P20B9 is a result of issues in specific components of your engine. These components are

  • Damaged DEF heater
  • Dirty DEF tank
  • Broken PCM

5 Common Symptoms Associated With The P20B9

If you see any of the following issues, it is best to test your car with an OBD2 scanner or take it to a mechanic right away-

● Check-engine light is on

If you see that your CEL is on, it means that your car needs immediate attention. Ignoring this signal is not a smart move.

● Poor engine performance

If you feel that your car is not performing to the levels that it usually does, there might be something wrong with your DEF heater. The deterioration in driving experience is noticeable.

● Bad fuel economy

As the DEF heater isn’t functioning properly, the engine can not efficiently use the fuel you put in. You are going to notice the sudden increase in gas expenses.

● Extreme emission of black smoke

This is rare but not unheard of. Sometimes, the lack of heating can lead the engine to emit large amounts of black smoke. 

● Related DTCs such as P20BA and P20BB

If you do hook up your car to an OBDII scanner, chances are you pick up some other codes such as P20BA and P20BB. These are closely related codes.

Read also >> P20BA Code On 6.7 Powerstroke: how to fix this error code?

How Serious Is Code P20B9 On Chevy?

Around 1.3 million people lose their lives due to road traffic accidents. A lot of these deaths could be avoided if auto-related issues were addressed immediately.

As such, car maintenance is vital. With a perfectly functional car, your safety is in your own hands. The code P20B9 cannot be taken lightly. Whatever vehicle you see this code in, you need to act hastily. Fix it or reach out to a mechanic as soon as possible.

Tools Needed For Diagnosis And Repair

Any successful repair needs you to arrange everything you need beforehand. So, I would like to start this article by telling you what things you need to gather to fix P20B9.

These are-

  • OBD2 Scanner 
  • Picking Kit
  • Socket And Wrench Set
  • Torch
  • Safety Gear

most common diagnostic errors

These are the most common reasons for misdiagnosis of P20B9:

  • Using a faulty OBD2 scanner
  • Misreading the DTC
  • Not having an ideal testing environment for the engine
  • Only relying on one test

How Do I correct My P20B9 Code 6.7 Powerstroke?

Now that you know all there is to know about the code P20B9, let’s finally get to fixing it. There are 3 methods you can go for to troubleshoot P20B9-

Method 1 >> Replace The DEF heater

The first method is the most complicated but it is most likely to fix your problem. So, wear your safety goggles, grab your tools and follow these instructions-

  • Step 1: Remove the skid plate by unfastening the various 13mm bolts, bolts, nuts, and fasteners holding it together
  • Step 2: Gently support the skid plate to the floor with your knees.
  • Step 3: Remove the 5mm bolts in the fuel door holding the DEF filler neck in place.
  • Step 4: Disconnect all the connections to the DEF tank except the injector hose
  • Step 5: Remove the 13mm bolts that support the DEF tank and gently place them down.
  • Step 6: Remove the injector hose with a gentle pinch
  • Step 7: Take off the module on top of the tank with your picking tools and 4mm Allen wrench
  • Step 8: Rotate the centerpiece till you hear a click.
  • Step 9: Remove the broken DEF heater
  • Step 10: Install the new heater
  • Step 11: Take her for a spin

Method 2 >> Replace the DEF tank itself

If for some reason, method 1 didn’t yield any results. There may be an issue with your DEF tank itself. It’s not uncommon for a tank to go through some wear and tear over the years. In most cases, they eventually become so dirty that they block out all filters.

This fix may cost you a bit but you should pray that it works because the next method is going to break the bank.

Method 3 >> Change the PCM

If both the previous methods fail and you’re still getting the same error, you may have an issue with your PCM. This is a nightmare because as I mentioned, this is the brain of your engine.

You need to replace it immediately. As this is a highly complex process, you cannot do it yourself. You need to go to a mechanic with expertise in this field.

How Much Does It Cost To Solve P20B9?

To solve P20B9, you need to spend quite a bit. I created this cost chart to give you an idea of how much it will cost. Not that all these are estimated costs.

Safety gearAll$150
ToolsDEF heater, DEF tank$200
New DEF reservoir heaterDEF heater$200
New DEF tankDEF tank$400
PCM Replacement (including mechanic charges)PCM$1000

Frequently Asked Questions (FAQs)

1. How To Tell What Each DTC Means?

There are hundreds of DTCs so having them all memorized is not feasible. Fortunately, there are many lists you can find on the internet. I found this one to include all the codes I came across most often.

2. Is The 6.7 Powerstroke A Top-Notch Engine?

Ford has been in the manufacturing game for ages and naturally, they’ve pretty much perfected the art. The 6.7L Powerstroke is an example of this perfection. This engine, made in 2011, is still used in 2022 in vehicles such as the Ford Super Duty.

3. Where Can I Buy A DEF Heater?

When buying auto parts, you have two options, going to a shop or buying them online. In my professional opinion, it’s always a good idea to go with the former. It is always a good idea to physically inspect your vehicle’s parts before purchasing them.

4. How Expensive Would A Mechanic Be?

This question is impossible to answer because there are so many varying factors here. Firstly, the hourly rates vary all over the globe. Secondly, the experience of the mechanic also matters. Those who are just starting won’t charge as much as seasoned veterans.

Thirdly and lastly, it depends on how long the task takes. The DEF heater replacement should be done in an hour. The other issues will take longer to solve.

P20B9 Duramax – Full Repair of DEF Heater >> Check out the video below:


Fixing P20B9 on a 6.7 Powerstroke is going to run up a tab no matter which method you use. My advice is to spend a little bit more and go for a mechanic. Professionals can repair your vehicle much faster and there is a lower chance of mistakes.

Who Worked on This?



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Mahir Ahmed


I'm the guy responsible for ensuring honest, informative, accurate and helpful guide to the reader.

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