P20B9 Code: Understanding Reductant Heater Issues & Solutions
Suddenly encountering the dreaded P20B9 code? No worries. We’re here to help!
The P20B9 code specifically refers to the Reductant Heater ‘A’ Control Circuit/Open. But what does that really mean for your vehicle?
In this article, we’ll provide a clear explanation of the P20B9 code, its severity, common symptoms, possible causes, and the necessary steps for diagnosis and repair.
Let’s get started.
Overview Of The P20B9 Code
To summarize, these are the main highlights of the P20B9 code.
- Definition: Reductant Heater ‘A’ Control Circuit/Open
- Severity: High
- DIY Skill Level: Intermediate
- Continue To Drive?: Yes (Warmer seasons only)
- Estimated Repair Cost: $50 – $500
What Does The P20B9 Code Mean?
The P20B9 code is a diagnostic trouble code (DTC) that indicates an issue with the reductant heater in your vehicle. A stored code P20B9 signifies that the powertrain control module (PCM) has detected the absence of voltage in the control circuit specific to the onboard reductant heater identified as heater “A.”
This code is commonly triggered in vehicles equipped with certain diesel engines, such as Ford Powerstroke (especially the 6.7 Powerstroke), Ram 2500 with Cummins engines, and cars that utilize Duramax engines.
(Image credit: Powerstroke.org)
In modern diesel vehicles, a reductant system reduces harmful emissions, particularly nitrogen oxides (NOx). This system utilizes a specific reductant known as diesel exhaust fluid (DEF) or AdBlue, which consists of a blend of urea and deionized water. The DEF is stored in a dedicated reservoir and introduced into the exhaust flow, where it undergoes a chemical reaction known as Selective Catalytic Reduction (SCR). This process converts NOx into nitrogen and water vapor, thus reducing emissions.
Within the reductant system, the heater plays a crucial role. It is responsible for heating the DEF to optimize its performance, especially during colder temperatures. The reductant heater ‘A’ refers to a specific heater element or circuit related to the DEF system. The control circuit ensures the proper functioning and regulation of the reductant heater. When the control circuit or the heater itself malfunctions or fails to operate within specified parameters, it triggers the P20B9 code.
How Serious Is The P20B9 Code?
While the P20B9 code may not cause immediate drivability problems, it should be considered a high-severity issue. You should address the P20B9 code as soon as possible, especially before the onset of colder weather.
During warmer seasons, the vehicle can still be driven without immediate consequences. However, it is essential to note that the DEF can freeze in colder temperatures if the reductant heater is not functioning properly. This can lead to severe damage to the DEF tank and related components.
Therefore, to avoid costly repairs and potential drivability issues, it is recommended to have the P20B9 code diagnosed and repaired promptly, particularly before the winter months. By addressing the problem promptly, you can ensure the proper operation of the reductant heater system and maintain optimal emissions control.
Read more: P2002: Diesel particulate filter efficiency below threshold
Potential Symptoms Of The P20B9 Code
The P20B9 code may be accompanied by the following symptoms:
- Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL) illuminated on the dashboard
- Reduced engine performance or power
- Increased fuel consumption
- Abnormal black smoke emitted from the vehicle’s exhaust
Common Triggers Of The P20B9 Code
The P20B9 code can be triggered by various factors, including:
- Open or short circuit in the reductant heater ‘A’ control circuit
- Faulty or damaged reductant heater
- Bad reductant temperature sensor
- Malfunctioning SRC controller/PCM or programming error
Read more: P2459 Code: Understanding, DIY Solutions, And Repair Costs
Step-by-Step Guide To Diagnosing & Fixing the P20B9 Code
Don’t let the P20B9 code leave you puzzled – follow our detailed guide, complete with step-by-step instructions, to diagnose and repair any issues affecting your vehicle’s reductant heater system.
Essential Tools And Parts
- OBD-II scanner or code reader
- Multimeter
- Basic hand tools (screwdrivers, wrenches, etc.)
- DEF heater element (if necessary)
- Wiring repair kit (if necessary)
Step-by-step Procedure
Step 1: Use an OBD-II scanner to retrieve the P20B9 code and any additional codes present.
Step 2: Inspect the reductant heater control circuit and wiring for any visible signs of damage or loose connections. If any issues are found, address them by repairing or replacing damaged wiring and ensuring all connections are secure.
Step 3: Test the reductant heater element for continuity using a multimeter. If it is faulty, replace it with a new one.
Step 4: Check the reductant temperature sensor for proper functionality. If the sensor is determined to be faulty, replace it with a new sensor.
Step 5: Verify the operation and communication of the reductant heater control module. Ensure that it is functioning correctly and communicating with the SRC controller/PCM. If any issues are detected, address them accordingly, which may involve repairing or reprogramming the control module.
Step 6: Clear the codes from the vehicle’s memory using the OBD-II scanner and test-drive the car to ensure the P20B9 code does not return.
Note: It is important to consult the vehicle’s service manual for specific instructions and specifications tailored to your particular make and model.
DIY Repair Level And Estimated Costs
The diagnosis and repair of the P20B9 code can range from moderate to advanced DIY repair skills, depending on the specific cause and complexity of the issue. Therefore, it is recommended to have a good understanding of automotive electrical systems and access to the necessary tools.
The estimated costs for repairing the P20B9 code can vary depending on factors such as the cause of the issue, the need for replacement parts, and whether the repair is performed by a professional mechanic or as a DIY project.
Here is a general breakdown of potential costs:
| Repair Task | Estimated Cost |
| Diagnostic fee | $50 – $100 |
| Wiring repair | $50 – $200 |
| Reductant heater replacement | $200 – $500 |
| Reductant temperature sensor replacement | $100 – $200 |
| Control module repair/reprogramming | $200-$500 |
Final Thoughts
Dealing with the P20B9 code is a common challenge among diesel vehicle owners. Therefore, it is crucial to understand how to effectively address this issue.
After reading this article, I hope you are now equipped with the knowledge to diagnose and resolve the problem confidently. Remember to use the appropriate tools and follow the step-by-step procedure outlined earlier.
If you have encountered the P20B9 code or any other OBD-II code, we encourage you to share your experiences and insights in the comments section below.
Stay knowledgeable and empowered in maintaining the performance and efficiency of your vehicle!