Can a Bad EGR Valve Cause a Misfire?

Too often car owners think that the issues their car is having are not a big deal or it will go away. They may be thinking there is no way a bad EGR valve can cause a misfire. Or that there may not be any other consequences of this. But are there?

What is an EGR Valve?

An EGR valve, also known as the exhaust gas recirculation system, maintains the chemical and thermal exhaust of your car’s engine. It’s main responsibility is to provide your car with a smooth operation, particularly during drawn-out rides. As it is doing this, it lowers the temperature of the engine and reduces chemical emissions from the exhaust. 

The EGR valve influences Nitrous Oxide, or Nox, emission. Your car will burn out the unused fuel while recirculating some of the exhaust. Therefore, fewer harmful emissions are let off by your car. 

Signs of a Bad EGR Valve

Many things can signal a bad EGR valve. You may see a reduction in overall engine performance, but there are also other signs that the valve is bad. 

Flashing Check Engine Light

If the check engine light is flashing, you may have a bad EGR valve. The electronic control unit may identify an issue in the emission control system. This will turn on the check engine light.

You can continue to drive with a broken EGR, but you will want to get it looked at as soon as possible. 

Fuel Consumption Increases

Fuel consumption will increase if the valve is left open. The fuel is not allowed to burn at full efficiency as the temperature will be too low. 

Trouble Starting the Engine

If you are having trouble starting the engine, there is a possibility the EGR valve is bad. The EGR valve should be shut when the engine is started. This will block the flow of gasses back into the engine.

Once the vehicle warms up and takes off, under normal circumstances, the valve will open. 

Should the EGR valve not be working properly, the exhaust fumes are allowed to pass into the combustion chambers. This causes the engine to cut out. If you smell fuel coming from the exhaust when starting the car, you could have a bad EGR valve. 

Engine Performance Decreases

If you notice a decrease in the performance of the engine, the EGR valve may be stuck open or closed. The engine may hesitate or sputter. Or you may even see a decrease in the fuel economy or notice a rough idle. 

Uneven Idle

Another sign that you have a faulty EGR is an uneven idle. If the EGR is engaged constantly and exhaust gasses get to the intake manifold, an unpredictable idle can occur. 


When your car is idling, if the valve is left open, the car may stall. When it is continuously left open, exhaust gasses can enter the EGR system. Thus, the car will typically stall with a rough idle. 

Engine Spark Knock

An engine spark knock comes from the engine bay while the car is accelerating or is under load. If the valve is blocked or not able to open as it should, the exhaust fumes are not permitted to re-enter the engine as they should. 

Smelling Gas

If you smell gasoline, a faulty EGR valve may be to blame. It is bad for your health to breathe in the NOx that is coming out of the tailpipe. And let’s face it…gasoline smells awful. Add in that when the valve is not working correctly, more fuel is burned.

This leads to more hydrocarbons release. Once these are mixed with the NOx, a harmful combination of gasses is produced. 

Failed Emissions Test

An emissions test ensures that the gas released by a car into the environment is not a threat to either lives or the environment. Some states mandate that it be completed every 6 months. 

Can a Bad EGR Valve Cause a Misfire?

Yes, a bad EGR valve can cause a car to misfire. The main cause of this is clogged-up passages that are located inside your vehicle’s intake. This will decrease the power of the car. 

A stuck valve can be caused by oil vapors that are inside the engine. This will increase carbon accumulations inside the exhaust gas recirculation valve. 

If the EGR valve is allowed to remain open, a large amount of exhaust gas will diminish the amount of air drawn inside. This will decrease the quantity of fuel injection from the control unit. The car will then misfire while you are driving it. 

Repairing or Replacing

When you have a faulty EGR valve, you need to consider repairing or replacing it. If it is clogged with soot particles, you may just need to have it cleaned so it is not stuck open or closed.

This can easily be done at home using a can of EGR valve cleaner. Using a can of professional EGR valve cleaner can be time efficient and is very easy. You do not need to remove the valve to clean it. 

Likewise, you can use a can of carburetor cleaner, but you will then need to remove the EGR valve. This is a harsh means of cleaning the valve, as it is time-consuming and you are exposed to an aggressive cleaner.

Or can ask your mechanic to clean it for you. If you opt to do it yourself, a can of cleaner should not cost you more than $20. 

If you need the EGR replaced, you can expect to pay up to $500 for the part and labor combined. This will depend upon the make and model of your car. Generally, a part can cost anywhere from $70 to $490. 

In Conclusion

A bad EGR valve can cause a misfire in your car, as well as many other costly repairs. Don’t have the mindset that if you can just hold out for a few more weeks or months, you will take the time to get it fixed. Get it fixed now before further issues arise. 

  • Eric Williams

    I'm the founder of Daily Car Tips. I wrote articles in the automotive industry for more than 10 years, published in USA and Europe. I love sharing my knowledge and insights with fellow enthusiasts. Join me on this journey as we explore the exciting world of cars together!

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