What is OBD-II Code P26A0 – Exhaust Aftertreatment Glow Plug Performance

P26A0 OBD-II Code – Exhaust Aftertreatment Glow Plug Performance

As a mechanic, dealing with OBD-II codes is a regular part of the job. One of the codes that you may encounter is the P26A0 code, which indicates an issue with the exhaust aftertreatment glow plug performance. This can cause problems with emissions and engine performance, so it is important to understand the code and how to address it. In this article, we will explain what the P26A0 code means, the possible causes, and how to troubleshoot and repair the issue.

What is the P26A0 OBD-II Code?

The P26A0 code is a generic powertrain code that indicates a fault in the exhaust aftertreatment glow plug’s performance. To understand this code, it is essential to know what the exhaust aftertreatment system is and what it does. This system is designed to reduce harmful emissions from the engine. It includes several components, including a diesel oxidation catalyst, diesel particulate filter, and selective catalytic reduction system. These components work together to reduce NOx, or oxides of nitrogen, which are harmful emissions.

Glow plugs are installed in the exhaust aftertreatment system to help reduce emissions during cold start. The P26A0 code is triggered when the engine control module detects an issue with the glow plug performance. The engine control module monitors the resistance of the glow plugs to determine if they are working correctly. When the resistance is incorrect, the P26A0 code is logged in the vehicle’s computer system.

Possible Causes of P26A0 Code

There are several potential causes of the P26A0 code, including:

1. Failed glow plug – If one or more of the glow plugs have failed, it can trigger the P26A0 code.

2. Bad wiring – If the wiring that connects the glow plugs to the engine control module is damaged or corroded, it can cause a poor connection that triggers the code.

3. Faulty glow plug control module – If the control module that regulates the glow plugs’ operation is not working correctly, it can affect glow plug performance and trigger the code.

4. Software issues – Sometimes, a software glitch in the engine control module can cause the P26A0 code to appear, even if there is no actual problem with the glow plugs.

5. Other issues with the aftertreatment system – Sometimes, other problems with the exhaust aftertreatment system can cause issues with the glow plugs and trigger the P26A0 code. This could include problems with the diesel particulate filter or the selective catalytic reduction system.

How to Diagnose and Repair the P26A0 Code

Diagnosing and repairing the P26A0 code can be challenging, but with the right tools and knowledge, it is possible. In most cases, it is best to start by checking the glow plugs and wiring to see if there are any visible issues. This can be done with a multimeter or other testing tools to check the resistance of the glow plugs and ensure that the wiring is not damaged or corroded. If there is an issue with the glow plugs’ resistance, they may need to be replaced.

If the glow plugs and wiring appear to be in good condition, the control module should be checked for proper operation. This can be done using a scan tool that can read engine codes and data. If the control module is not working correctly, it may need to be replaced.

In some cases, the P26A0 code may be triggered due to software issues. If there are no visible or apparent problems with the glow plugs, wiring, or control module, the engine control module’s software may need to be updated or reprogrammed to resolve the issue. This can be a more complex process, but most mechanics will have the tools and knowledge to resolve the issue.

Frequently Asked Questions

1. What causes the P26A0 code?

The P26A0 code is typically caused by one or more failed glow plugs, poor wiring connections, a faulty control module, software issues, or other problems with the exhaust aftertreatment system.

2. What are the symptoms of the P26A0 code?

In most cases, there will be no noticeable symptoms when the P26A0 code is triggered. However, if the code is not addressed, it can lead to poor engine performance and increased emissions.

3. Can the P26A0 code be ignored?

While the engine may still run with the P26A0 code present, it is not advisable to ignore it. Ignoring the code can lead to increased emissions and potentially more serious engine problems over time.

4. How is the P26A0 code diagnosed?

Diagnosing the P26A0 code typically involves checking the resistance of the glow plugs, checking wiring connections, and examining the glow plug control module and engine control module for any issues.

5. Can the P26A0 code be repaired by a DIY mechanic?

While it is possible for a DIY mechanic to diagnose and repair the P26A0 code, it can be challenging and typically requires specialized tools and knowledge. In most cases, it is best to have a qualified mechanic address the issue.


The P26A0 OBD-II code can be a frustrating issue to deal with, but with the right tools and knowledge, it can be resolved. Whether you are a professional mechanic or a car owner looking to understand the issue better, the information in this article should help you understand what the code means, the possible causes, and how to diagnose and repair the issue.

Additional Resources

If you want to learn more about OBD-II codes and how to diagnose and repair engine issues, there are many resources available online. Websites like OBD-Codes.com and AutoZone.com offer helpful information and resources for DIY mechanics and car owners. Additionally, many automotive forums offer a wealth of knowledge and experience from real-world mechanics and car enthusiasts.

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