Tech Tips: Why Is My Diesel EGR Valve Failing? 5 Common Causes

An EGR or exhaust gas recirculating valve is a key part of any modern diesel engine. Unfortunately, they have gotten a bad reputation over the years as being one of the most common parts to fail on an otherwise durable engine.

In an attempt to reduce emissions, manufacturers introduced the EGR valve on all modern diesel engines. It works by recirculating a portion of the exhaust gasses back into the motor, which helps reduce the overall pollution.

EGR422 CUMMINS ISX EGR VALVEAt the first sign of failure, some owners will choose to bypass the entire system as opposed to repairing it. But did you know that this can cause more harm than good? Turbocharged diesel engines are designed to work in conjunction with the EGR valve as well as other key, emissions systems. 

Why does your EGR valve fail? What causes it to become stuck open or closed? What can be done to prevent future EGR valve issues? We, at Highway & Heavy Parts, will be answering these questions alongside many others in this post. Read more below!

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5 Common Symptoms Of A Failing EGR Valve

There is no question about it. When compared to gasoline, the diesel engine produces comparably more pollutants such as NOx and carbon dioxide. Luckily, engine manufacturers have introduced several methods of reducing the overall amount of pollutants from entering our atmosphere. They include but are not limited to, catalytic converters/DPF, DEF systems, and of course EGR valves. 

Let’s have a look at some of the common signs which point to a failing EGR valve: 

1. Rough Idle 

Any change in RPM at idle should be cause for concern. A “sloppy” or rough idle can be caused by one of several things. One of the reasons that your truck may have a rough idle is due to a defective EGR valve that is stuck in the open or closed position.  

2. Excessive Smoke 

Modern diesel engines produce next to no smoke. Coal rolling, locomotive-like engines are now a thing of the past. Any signs of excessive smoke should be taken note of and investigated as soon as possible to avoid further issues.

3. Increased Fuel Consumption 

If you spend hours behind the wheel each day, chances are that even the slightest increase in fuel consumption will get noticed. One of the first things to check is the EGR valve. A defective exhaust gas recirculating valve could be the culprit. 

4. Decreased Engine Performance

Does your truck feel sluggish? Does it not have the same amount of acceleration as it once did? Something as simple as a defective EGR valve could be to blame. 

5. Check Engine Light

Cars, trucks, tractor-trailers, and almost anything else with an engine that is on the road today will have some sort of ECU controlling all the parameters to make sure everything is in good working condition. If your check engine light comes on, the best thing to is to have the codes scanned to fully determine the issue.

To learn more about EGR valve problems and what may cause them, check out our other post here!


What Causes An EGR Valve to Fail?

EGR valves are subjected to extreme working conditions. Over time, like many other mechanical parts, it will fail if not maintained properly. When that time comes, we are here to help get you back on the road as soon as possible. 

In most cases, an EGR valve will fail by getting stuck open or closed due to built-up carbon deposits generated from the exhaust gas. 

diagram of an egr valve stuck closed

A closed EGR valve will create an increase in NOx or nitrous oxide, which will have incomplete combustion as a byproduct. The end result is usually an engine knock, which will be picked up by the engine’s ECU, affecting overall performance. 

diagram of an egr valve stuck open

Alternatively, if the EGR is stuck open, issues such as rough or poor idling can happen due to excessive exhaust gas being present in the intake. To compensate, the ECU will add extra fuel for combustion. The end result being even soot- or carbon buildup in the system. All this adds up to an increased potential for problems with your engine, turbocharger, and most other combustion components. 

Do you think your diesel engine has a carbon buildup problem? Have a look at our other article about removing carbon from your engine here! 

If you think the engine is suffering from a defective EGR valve, don’t be tempted to just delete it. Remove it and replace it with a new one. After all, the truck was engineered to work with it.

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Why Deleting Your EGR Valve Is Not A Good Idea 

Although removing your EGR valve may seem like a good idea if it has stopped working, several key things should be taken into consideration. Initially, it may seem like the logical choice as new ones are quite expensive. After all, the engine can run without it, right? 

Yes, the engine can run without an EGR valve, but it can have severe consequences. Firstly, the financial decision of not replacing the exhaust gar recirculating valve can quickly be outweighed by the fact that it is illegal and faces the potential of up to five-figure fines from authorities.

Additionally, modifying your diesel engine now can have complications later on. As previously mentioned, diesel engines are complicated. All data is processed by the computer or ECU, and any changes in air/fuel mixture will cause it to try and compensate by adding or taking away fuel, depending on the situation, increasing the chance for carbon buildup.

No matter how you look at it, deleting your EGR valve is not a good idea. Saving a little will only prove to be a bad idea in the long run. Do it the right way, replace the EGR valve, and help keep your truck running right! 

What Can Be Done To Prevent EGR Valve Problems? 

Prevention is key! Keeping everything in good running condition is the best form of insurance. We know that EGR valves are not popular as they further complicate the engine, but it is a necessary evil. 

Cleaning the EGR valve and intake system is another way of helping it last as long as possible and it should be considered a regular service item, especially on high mileage trucks.


Final Words

If your EGR valve has finally met its match and needs to be replaced, Highway & Heavy Parts will help get you back on the road promptly. We have a variety of exhaust gas recirculating valves in stock and ready to ship out today. 

Our ASE-certified techs are ready to stand by and ready to answer any questions you might have about the EGR valve or most other diesel engine parts. Give us a call at 1-844-985-3408 or request a quote online right now! 

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