What Is P20B9 code on 6.7 Powerstroke: How To Fix?

Ford 6.7L engines throw a bunch of DTCs (Diagnostic Trouble Codes) to inform users about the irregularity of their engines. The error code P20B9 is one of them. 

If you’re getting the DTC P20B9 & don’t know what it means, this article is for you. In this article, I’ve discussed every possible way of solving this error code along with symptoms & causing factors. 

P20B9 Code On 6.7 Powerstroke

What Does P20B9 Code Means On 6.7L Powerstroke? 

PD209 is one of the diagnostic trouble codes of the Ford 6.7L engine. By definition, this error code means Reductant Heater A Control Circuit/Open. 

When the PCM (Powertrain Control Module) detects zero-voltage of the reductant heater A, it stores the DTC P20B9. You might be wondering, why is it marked with the letter “A”?

Well, three on-board reductant heaters are located in the control circuit. To specify & navigate them correctly, they’re named Reductant Heater A/B/C. 

The DEF (Diesel Exhaust Fluid) tank needs heater A to prevent the fluid from freezing up. When heater A cannot produce heat due to no voltage, the error code P20B0 shows up. 

Symptoms Of Getting The P20B9 Code On A 6.7

Just like every other DTCs of the Ford 6.7L engine, P20B9 comes with some visible symptoms. Expect to have a P20B9 error code if you’re noticing some of these symptoms mentioned below:

  1. Check Engine Light (CEL) is Active 
  2. Excessive Black Smoke From Exhaust Panel
  3. Poor Fuel Economy or Mileage Per Gallon (MPG)
  4. Sluggish Driving Experience
  5. Other Selective Catalytic Reduction Related Codes 

Be sure of getting this DTC if you’re having three or more symptoms mentioned above. 

The Causing Factors Of The Error Code P20B9

This code is all about the heater A being defective. It’s obvious that the causing factors of this error code will be related to the heater A, such as:

  • Faulty Reductant Tank Heater A
  • Open or Shorted Harness Of Reductant Heater 
  • Poor Electrical Connection Related To The Heater 
  • Shorted or Failed DEF Supply Line 
  • Damaged PCM/SCR (Rare Case)

Any of these mentioned causes is enough to bring up the DTC P20B9 & mess up your driving experience. 

How Seriousness Is Code P20B9 On 6.7L Powerstroke 

The seriousness of this code depends on the weather condition. If you’re living in a warm region & this code pops up, you won’t have to be as panicked as someone from a cold region. 

In summary, fix this code as soon as possible if you’re living in cold weather. If the DEF (Diesel Exhaust Fluid) freezes up, it can harm the DEF tank severely & you wouldn’t want that to happen. 

How to Solve P20B9 Error Code On 6.7L Powerstroke?

You may think replacing the reductant heater A can only eliminate this code, but no – other ways of solving this code are also available. 

Before proceeding to the fixing operation, make sure to have your equipment ready. You’ll need equipment, such as:

  1. Safety Goggles, Gloves & Flashlight 
  2. Scanner & DVOM (Digital Volt/Ohm Meter)
  3. Correct Sized Socket, Ratchet & Extensions

If you’re ready with the equipment, let’s get started with the troubleshooting methods:

Check The SCR Control System

You’ll need the DVOM to test your SCR (Selective Catalytic Reduction) control system. First, test the fuses. Make sure the circuit is loaded to avoid misdiagnosis. 

If you’re noticing reasonable battery voltage & ground circuits, head over to the next step. Activate the heater/s with the scanner & check output control voltage. Replace the SCR controller if the voltage is insufficient. 

Replace The Temperature Sensor

It’s possible that your temperature sensor is damaged & it’s sending wrong information to the PCM. Later on, PCM is ‘thinking’ diesel exhaust fluid is about to freeze & splits the DTC P20B9. 

Consider replacing the temperature sensor & clear the code. If the code reappears after a few minutes of driving, suspect the reductant heater A. 

Replace Broken Glow Plugs 

Broken glow plugs tend to reduce engine performance over time. If you’re noticing your glow plugs broke, about to break – replace them with a new set of glow plugs. 

Doing this low-cost task can fix your P20B9 error code if you’re lucky enough. If not, follow the next method & it should be the ultimate cure for this DTC. 

Check & Replace Reductant Heater A

Check wirings, hoses related to the reductant heater A. Don’t forget to check the electrical connectors while visually inspecting. Use proper equipment to reach Heater A. 

If you determine the heater is the main culprit – replace it as soon as possible.

How Much Does It Cost To Solve The Error Code P20B9?

Considering you need to replace the reductant heater A to solve this error code, you’ll have to spend $300 to $500 on the heater itself. 

Additionally, you can choose to install this heater on your own to save another 150+ bucks on labor cost. If luck isn’t in your favor, you may end up replacing the PCM for $500 (without labor cost). 

Common Mistakes While Solving The P20B9 Code

Be very careful while solving the P20B9 code. Don’t make these common mistakes mentioned below:

  • Not Checking The Temperature Sensor Before Replacing The Heater 
  • Not Checking Everything Else Before Replacing The PCM

Additional Comments To Consider Regarding The P20B9 Code 

The freezing point of diesel exhaust fluid is -11° Celsius or 12° Fahrenheit. If you’re living somewhere warmer in comparison to the freezing point of DEF, you don’t have to worry about it (initially). 

However, I highly recommend getting rid of this code as soon as possible despite your weather condition. If you keep ignoring this code for a longer period, your engine may catch bigger damages.  


I hope this article was informative enough to know the DTC P20B9 properly. Now you can inspect & repair this error code on your own. 

You can fix this error code even if you’re new to the Ford 6.7L engine. Yes, you’ll need to take professional help if your PCM is faulty & needs to be replaced.

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