6 common EGR Valve Symptoms on Duramax (easy solutions)

Did you experience rough idling or higher fuel consumption recently? These might be signs of a faulty EGR valve on your Duramax truck. If so, let me inform you that you are affecting both your truck and the environment around you.

Besides rough idling or high fuel consumption, poor performance, stalling, increased engine knocking, etc., can be the main symptoms of a faulty EGR valve. If you ever see any of these symptoms, know that you need to work on the EGR valve.

I am about to tell you about the purposes of an EGR valve, the common symptoms of a faulty EGR valve, what causes the issues, and how to fix such a valve in this write-up.

6 common EGR Valve Symptoms on Duramax (easy solutions)

Purpose of an EGR Valve

So, what is an EGR valve, and what does it actually do? As you might know, diesel engines usually have higher compression ratios. When the air and the fuel mixture are ignited, the combustion chamber temperature can go up to 1,370 degrees Celcius.

At this temperature, about 80% of the Nitrogen present in the air gets burned with the help of about 20% Oxygen and creates Nitrogen Oxidesn (NOx). When this oxide is emitted into the atmosphere, it pollutes the air and causes several respiratory problems in humans.

An EGR or Exhaust Gas Recirculation valve is used in Duramax engines to fight this emission. These valves recirculate the exhaust gas into the engine’s intake manifold and cool the gas down to reduce NOx emissions. Apart from environmental concerns, there are many other benefits of EGR valves.

6 most Common Duramax EGR Valve Symptoms

If the EGR valve in your Duramax engine doesn’t work properly, it can cause various issues like power loss, decreased acceleration, and poor fuel efficiency. Here will be some common EGR failure symptoms so that you can recognize the problem faster.

1. Rough Idling

You might experience your Duramax engine revving up abnormally when you start the vehicle or put it on idle for some time. If the rev goes up automatically, it is probably because of an open EGR valve. Due to the free flow of the exhaust gas to the intake, the engine will rev more than usual.

2. Derated Performance

If you suddenly feel your Duramax engine isn’t performing as expected, it might be caused by a bad EGR valve. The wrong position of the valve can also cause this problem.

3. Decreased Fuel Efficiency

You get the maximum fuel efficiency from a Duramax engine when the EGR valve opens and closes in the right situations. If the valve is always open, the temperature will be lower than optimum and prevent fuels from burning completely. This will result in decreased fuel efficiency and a clogged EGR cooler due to excessive soot deposit.

4. Smell of Fuel

As I have already mentioned, the fuel won’t properly burn if the EGR valve remains open all the time. So, you might smell fuel from the exhaust gas, and it will increase the emission of hydrocarbon from the engine.

5. Check Engine Light Comes On

If you are a new user of a Duramax engine and don’t notice the previous symptoms, this is the last resort. You might see the check engine light getting illuminated on the dashboard. But remember, the light might not come on until the EGR valve is completely damaged.

6. Engine Knocking

A stuck closed EGR valve causes this. As the amount of NOx rises inside the system, the engine will produce more knocking than usual.

What Causes EGR Valve Issue on Duramax?

The main cause behind EGR valve issues on a Duramax engine is the soot. To be more specific, the EGR valve tends to cool down the flame temperature to emit less NOx into the environment.

The biggest problem here is the number of unburnt hydrocarbons. Due to the lower oxygen concentration in the air-fuel mixture and lower temperature in the combustion chamber, Duramax engines emit about 20-30% more hydrocarbons than other engines without EGR valves.

As the soot emission gets higher because of EGR valves, carbon and other particles usually get deposited in these valves. Though this doesn’t affect the performance of the engine at lower loads, you might experience a loss of boost at higher loads.

The use of an EGR valve also reduces the number of emissions, which is another cause of the excessive particle deposit inside the valves. As long as the valve can open or close gradually, the engine will run just fine.

But when the valve is stuck open or close due to the excessive buildup, problems start to occur, and the symptoms begin to be visible.

How to Fix Duramax Faulty EGR Valve?

If you see your Duramax EGR valve showing signs of fault, you should first determine the valve’s position. The valve can either be stuck open or closed, determining the category of issues. Here will be a short guide on how you can fix a Duramax faulty EGR valve.

  • The first thing you should do is to remove the EGR cooler vacuum line. If you see any sign of damage on this line, you should replace it right away.
  • Most modern EGR valves are electromagnetic. So, you need to disconnect the electric wiring from the valve.
  • The valve may be attached to the engine with bolts. Turn those bolts open and take off the valve assembly.
  • Soak the valve into a carbon cleaner. Leave the valve overnight to dissolve the deposits completely.
  • Use a toothbrush or small pipe cleaner to unblock EGR valve. Try to remove as much crud as possible from the valve.
  • After the valve is completely cleaned and dried, reinstall it to the system and make sure all connections are in place. By now, the valve should work fine. If the issues remain, take your vehicle to a certified technician for Duramax EGR bypass valve replacement.

people also ask (FAQ)

I answered a few common questions regarding Duramax EGR valve symptoms. Check them out.

How do I know if my Duramax EGR valve is working?

Know that your Duramax EGR valve is working fine if your vehicle is performing as expected, has a very good fuel economy, and doesn’t show any signs of rough idling, stalling, or knocking.

What happens if the Duramax EGR valve is stuck open?

When the valve is stuck open, problems like rough idling, weak accelerations, stalling, etc., can happen.

When to clean your Chevrolet Duramax’s EGR valve?

It depends on the instruction of the manufacturer. Generally, EGR valves on a Chevrolet Duramax can run up to 50,000 miles before they need to be cleaned.

Can you clean EGR valve by driving?

If you want to clean EGR valve without removing it, you can warm up the engine and spray an EGR valve cleaner to clean the valve.

Symptoms of a bad EGR valve (Rough Idle, Shaking, Engine Misfire) >> Check out the video below:

Final Words

Though an EGR valve is a small part of a Duramax diesel engine, it has a great role in controlling the emission. While doing this, the valve faces some serious abuse and may get blocked in one position. This abruption in the movement of the valve results in some distinctive symptoms. If you know these symptoms, it will be a lot easier for you to determine whether the EGR valve on your Duramax is faulty or not.

I tried to compile all my knowings about Duramax EGR valves so that you know the common issues and their solutions. Try these solutions before taking your vehicle to the service center.

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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