What Is P249D Code On Duramax: How To Fix?

P249D code Duramax indicates a limitation on the amount of fuel that can be injected into the engine. In addition, this can be caused by a problem with the reductant injection control system.

If the reductant injection control system is not working properly, very low fuel will be injected into the engine. And it can result in decreased engine performance and increased emissions.

The code can be determined by examining the vehicle’s diagnostic system.

When you suspect about your Duramax has a problem, you should go to a mechanic as soon as possible.

P249D code Duramax

What Does P249D code Mean on Duramax?

P249D code means a “mean on Duramax means limited flow on reductant injection control.”

The code is typically seen when the air/fuel ratio (AFR) is too high and the engine’s computer (ECU) isn’t able to regulate the flow of fuel properly.

Moreover, this can lead to a “mean on” condition, where the engine’s pistons are constantly pushing and pulling against each other, which in turn can damage the engine.

When this code is set, the manufacturer recommends using a reduced flow rate of injection.

And, this can lead to decreased fuel economy and increased emissions.

To avoid this problem, drivers should check their vehicle’s P249D code and adjust their injection accordingly.

How serious is the P249D code on Duramax?

The Duramax engine found in some trucks and SUVs is susceptible to a code P249D, which means the engine has low fuel inactivity. In addition, this problematic code can cause significant problems, including loss of power, poor fuel economy, and even an engine fire.

If you’re experiencing any of these symptoms, it’s important to get your truck or SUV checked out by a mechanic as soon as possible.

What Are the Symptoms of P249D CODE?

Duramax engines are some of the most powerful and efficient in the automotive world.

However, like any high-performance engine, they can also cause problems if not maintained properly. In particular, P249D code Duramax engines can experience problems with their

  • Turbochargers,
  • Fuel systems,
  • And exhaust systems.

If not diagnosed and repaired quickly, these issues can lead to serious engine damage or even a fire.

When your Duramax truck has the “Engine Light ON or Service Engine Soon Warning Light” code P249D, there are potential symptoms you should be aware of.

The most common symptom is a loss of power, but other possible symptoms include

  • Poor fuel economy,
  • A rough idle,
  • And an inability to start the engine.

When you experience any of these symptoms, it’s important to take your truck to a mechanic as soon as possible for an evaluation.

The Causing Factors of the Error Code P249D Duramax

Duramax engines are known for their powerful performance and longevity.

  • Yet, like any engine, they can experience exhaust leaks and fuel contamination. And it can cause the P249D code.
  • Also, an engine code P249D is associated with a malfunctioning diesel particulate filter (DPF).

A DPF cleans the exhaust gas of harmful particles, such as soot and smog, before it enters the atmosphere.

If the DPF is not working properly, these particles can build up in the engine and cause the code. In some cases, a faulty DPF can also cause the Duramax engine to misfire.

  • A faulty NOx sensor on a Duramax diesel engine can cause the P249D code.
  • The problem can be caused by a build-up of diesel exhaust fluid (DEF) on the sensor, which can cause it to malfunction.

When this happens, the engine may not be able to properly detect and correct air-fuel mixture problems, leading to decreased fuel economy and performance.

How Do I Fix My Duramax P249D error code?

Looking to fix your Duramax P249D? Here are a few steps you should take to ensure the repair goes smoothly:

  • Check for damaged components and look for broken, bent, pushed-out, or corroded connector pins.
  • If any of the damage is severe, replace the component(s).
  • Verify all electrical connections are secure and correct.
  • Make sure the engine is properly lubricated and cooled.
  • A broken connector pin can cause a Duramax P249D to not start. If the pin is bent, pushed out, or corroded, the engine could fail catastrophically.

A technician must check for damaged components and look for broken, bent, pushed-out, or corroded connector pins to fix the P249D.

How Much Does It Cost To Solve theP249D?

If your Duramax is giving you trouble, it’s time to take it in for repair.

But before you do, be armed with the knowledge of what you’re likely to pay for an hour of work.

The average cost for a mechanic to diagnose and fix a P249D code Duramax is between $75 and $150 an hour.

However, Duramax engine problems can be costly to fix, and there’s no one-size-fits-all answer to figuring out the cost.

Depending on the severity of the problem, some repairs may only require a simple adjustment.

Also, more complex repairs may necessitate a complete overhaul.

Common Mistakes When Diagnosing the P249D Code

When diagnosing the P249D code on a Duramax diesel engine, there are a few common mistakes that can be made.

  • The first is to assume, all of the symptoms are related to the fuel system.
  • Another mistake is to assume only serious problems will result in a code.
  • Finally, it’s important to understand the different emissions codes that can be caused by the P249D problem.

people also ask (FAQ)

1. Is it OK to drive with an exhaust leak?

The exhaust gases include carbon monoxide, which is why riding with an emission leak may be deadly.

2. How much does it cost to fix an exhaust leak?

The cost of repairing an exhaust leak ranges from $100 to $400, while the cost of replacing the whole exhaust system may run from $150 to over $1200.

3. What happens if fuel is contaminated?

Fuel contaminated with impurities can soon clog the filter. When water seeps into the gasoline, it may damage pump elements, leading the pump to stop working altogether. A blocked fuel filter might result in the sluggish performance of the engine.

4. Can you drive with a faulty DPF filter?

Neither driving a diesel vehicle without a DPF nor removing the DPF from your vehicle is permitted under current law. Your car’s engine might be damaged if you drive with a faulty DPF filter.

5. Can I drive with a particulate filter Warning?

To avoid damage, your vehicle will enter restricted performance mode’ if you disregard a DPF warning light and drive in a sluggish, stop/start pattern. If you allow things to deteriorate to this point, no amount of speeding will suffice.

Final Words

The P249D code Duramax is a result of a problem with the fuel injectors on a Duramax engine.

There are several possible causes for this code, and the best way to fix it is to determine the cause and then repair it.

Also, there are several ways to do this, so be sure to consult a mechanic if you are not familiar with repairing these engines.

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Who Worked on This post?



Anderson is an experienced auto mechanic with over 10 years in the industry. He is skilled in diagnosing and repairing a wide range of vehicles, from sedans to trucks and SUV

Syed Ahmed


Syed Ahmed has been working as an auto mechanic editor for the past five years. He has a background in mechanical engineering and a love for all things automotive

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