What Are The Symptoms Of A Faulty EGR Valve?

A bad EGR Valve causes poor performance or decreased mileage. Here are the key symptoms to remember and why you shouldn't ignore this particular issue.

If you’ve ever driven through a major city like LA, Chicago, New York, or Denver, then you’ve likely seen air pollution first-hand.

Fortunately, exhaust gas recirculation technology was added to cars in the form of an EGR valve.

What is an EGR valve, and what signs suggest that yours is failing?

The EGR valve has one purpose, to reduce the NOx pollutant (nitrogen) emitted by your vehicle. It does this by recirculating some of the emissions back into the combustion chambers rather than sending them outward.

Some signs of your EGR valve failing include a rough idle, poor performance, or decreased mileage!

Thankfully, we will cover everything you ever want to know about an EGR valve in this thorough guide. We will first take a closer look at what an EGR valve is and how it operates.

Afterward, we will examine the eight most prevalent signs that indicate yours is failing.

Let’s cover the basics!

Table of ContentsShow

What Is An EGR Valve, And How Does It Work?

EGR Valve 1

Your vehicle requires oxygen to function. The issue is that the air it draws in from outside is about 80% nitrogen and only 20% oxygen. Fuel is then mixed in with this and ignited inside the combustion chamber by the electric spark plugs.

When the nitrogen is burned, it gives off what’s known as nitrogen oxide (NOx), the primary pollutant that the EGR valve was designed to reduce.

While an EGR valve might sound like an intricate device, it’s actually quite straightforward – a valve that stays open or closed. It either allows exhaust gas back in or sends it out the tailpipe.

There are two types of EGR valves, one that’s operated by a vacuum and one that’s electronically controlled by the ECM.

What is the benefit of an electronically controlled EGR valve? Simply put, it’s able to optimize its position based on readings from the ECM, meaning it’s more efficient. Because of this, most modern cars favor this over a vacuum-operated valve, which is usually only found on older vehicles.

The 8 Most Common Symptoms Of A Bad EGR Valve

Reason #1 – The Engine Is Idling Rough

car engine

If your EGR valve is stuck in the open position, it can allow too meager or too abundant exhaust gas into the combustion chamber.

This can throw off the air/fuel mixture inside (which needs to be exact) and cause the engine to idle irregularly.

Reason #2 – Your Fuel Economy Lowers

how to improve gas mileage

Another side-effect of an EGR valve being stuck open is a decline in fuel economy.

This happens due to the temperature inside the combustion chambers being chillier. This means the fuel inside does not ignite as swiftly or effectively.

Reason #3 – Your Car Stalls While Idling

opening the hood of a broken car

Similar to the first reason, an EGR valve stuck in the open position can also cause your engine to stall while motionless.

While this isn’t as hazardous as a car stalling while driving, it certainly demands your attention to ensure it does not keep occurring.

Reason #4 – The Engine Performance Drops

man in car driving through street

If you observe a decline in performance, like when accelerating, it might be because your EGR valve is stuck either open or closed. This can manifest in various forms, such as a coarse idle, reduced fuel efficiency, sputtering, or hesitation.

Why does this occur?

The air/fuel mixture inside the combustion chambers is inaccurate. If the valve is stuck open, it allows too much exhaust gas in; if it’s constantly closed, your emissions will increase.

Reason #5 – You Notice The Smell Of Gasoline

man and bad smell inside car

The EGR valve was created to reduce the harmful NOx emissions from your vehicle’s exhaust that can adversely affect your health.

Not only that, but it also carries a foul odor.

Additionally, when your EGR valve is not functioning correctly, your engine may burn more fuel, which releases hydrocarbons. These mix with the added NOx and create a hazardous blend of harmful gases.

Reason #6 – Your Vehicle Produces More Emissions

car diagnostic exhaust gas measurement at diagnostic station

Many states have rigorous emission standards, requiring testing to be done every 6 months or so.

If your car recently failed one of these tests, it might be due to a faulty EGR valve. Driving a vehicle that has not passed a state inspection can result in hefty fines.

If this coincides with any of the other signs of a defective EGR valve, then it is likely the cause.

Reason #7 – The Check Engine Light Stays On

car check engine light on

A check engine light may not appear if your EGR valve is simply failing. However, when it does actually call it quits, you’ll likely see one then.

For this reason, if your check engine light does illuminate and coincides with some other elements, it may be the EGR valve.

Remember, an electronically regulated EGR valve receives its data from the ECM. The ECM is also in charge of illuminating the check engine light. If the air/fuel mixture is off inside your combustion chambers, it’s likely to provide a caution.

Reason #8 – The Engine Makes A Knocking Sound

car shuddering while driving

If the EGR valve is stuck in a closed position, the temperature inside the combustion chambers will be intense. This leads to the fuel igniting too early when the engine is at low RPM, which can cause a knocking sound.

What Happens If You Ignore A Faulty EGR Valve?

man and woman with broken car

If you’ve read through the above list of symptoms, then determining why it’s a dreadful idea to ignore a defective EGR valve is not that difficult.

Reduced fuel economy, a rough idle, stalling, and the persistent smell of gasoline? Eventually, these symptoms will become too extreme to handle, and you’ll need to figure out a solution.

If your car fails a state inspection, it means you’re not legally allowed to drive it without risking a penalty. If you get pulled over while driving a vehicle that’s not eligible, it will likely get impounded.

This means you’ll not only have to pay the initial fine – but impound fees as well.

Thankfully, in the following section, we will cover your options and what they cost.

Cost To Replace An EGR Valve

EGR Exhaust Gas Recirculation

Repair or substitution – that is the question.

For replacement, costs can reach more than $500, including both components and work. Though this can also be as low as about $150, depending on the make and model of your vehicle.

Thankfully, if the EGR valve is merely clogged and is stuck open or closed due to soot particles, it may just need to be cleaned. If you’re fairly comfortable under the hood, you should be able to do this yourself at home using a spray can of EGR valve cleaner.

This should cost about $15 for the cleaner and between $70 to $490 for the component.

The EGR Valve – A Small Step In The Right Direction

heavy traffic in highway

We don’t have a plethora of options when it comes to planets that support life. For this reason, don’t you owe it to yourself and those around you to take care of a faulty EGR at the first signs of an issue?

By doing so, you not only ensure that the air coming out of the tailpipe is as clean as possible, but you preserve the effective operation of your engine as well.

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Joshua Barrett

Josh Barrett is a writer hailing from the great state of Alaska. While describing himself in the third person is not his forte, writing about any and all things automotive – is. After 13+ years hustling in the exciting world of car sales, he took off to travel the world with his dog Teemo.