Most Common Symptoms of Bad EGR Valve

by Petra CameronMarch 23, 2022

The exhaust gas recirculation (EGR) valve is an automobile component that is critical in controlling exhaust emissions.  Every advanced car is equipped with an EGR valve. When it becomes clogged or broken, it may result in poor engine performance, decreased mileage, and rough idle.

When inspecting a bad EGR valve, several indicators should be observed, including engine check light, the smell of unburnt fuel, poor engine performance, a rough idle, and a failed emissions test.

How Does An EGR Valve Work?

A car requires oxygen to run. The air draws in from the outside is roughly 80% nitrogen and 20% oxygen. The fuel is then mixed in and combusted by the spark plugs within the combustion chamber.

This combustion process produces nitrogen oxide, also referred to as NOx. This byproduct is one of the most harmful pollutants produced by automobiles, posing serious health risks. 

The EGR valve serves a single purpose: to reduce the amount of NOx (nitrogen) emitted by your vehicle. This is accomplished by recirculating some of the exhaust gases back into the combustion chambers rather than discharging them.

Symptoms of Bad EGR Valve

Bear in mind that the same performance issues that indicate a faulty EGR valve could also signal a problem with another component of the system. While there are numerous negative symptoms, the following are the primary signs that your EGR valve requires attention.

Engine Warning Light

When your vehicle detects a problem with the EGR valve, the engine management light may remain illuminated. This could occur as a result of the EGR being constantly closed or open. It is worth noting, however, that the EGR valve typically begins to degrade long before it fails completely, and the engine management system may not detect this until the valve fails completely.

Rough Idling of the Engine

If your EGR valve is stuck open, it may allow insufficient or excessive exhaust gas into the combustion chamber. This can distort the air/fuel mixture inside the engine, resulting in a rough idle.

Lower Fuel Economy

A faulty EGR valve may also result in a decrease in fuel economy. This occurs as a result of the lower temperature inside the combustion chambers. Because of this condition, the fuel inside is not igniting as quickly or efficiently as it should.

Poor Engine Performance

Perhaps the most troubling issue is the engine's performance. When you step on the gas pedal, there is a good chance that you will experience acceleration problems and possibly an overall loss of engine power. This can also occur as a result of a clogged fuel filter.

Unburnt Fuel Smell

Now that the EGR valve is not operating properly, the engine is consuming more fuel than it should, resulting in increased hydrocarbon emissions from the tailpipe. This will significantly increase the amount of fuel odor, to the point where you can smell it inside the car if your air conditioner is not set to recirculation mode.

Failed Emissions Exam

If you are required to test for increased emissions every six months, there is a possibility that you have a faulty EGR valve. While this test may not predict exactly the condition of the EGR valve, if you fail your emissions standards, it is advisable to have the vehicle's EGR valve inspected by a professional.

What To Do If You Have a Bad EGR Valve

If your vehicle exhibits any of the above-mentioned EGR valve symptoms and you suspect that you have a broken valve, it is recommended to have your vehicle inspected by a qualified mechanic. With the proper diagnostic equipment, EGR faults can be easily diagnosed.

If your car fails a safety inspection, you are legally prohibited from driving it without incurring a fine. If you are pulled over while driving an ineligible vehicle, it will almost certainly be impounded. This means that you will be required to pay not only the previous fine but also impound service charges.

Two Types of EGR

An EGR valve has two types: one that is electronically controlled by the ECM and one that is vacuum operated. Generally, electronically controlled EGR valves are more efficient because they can adjust their position in response to ECM readings.

Vacuum Operated

EGR valves took up more space in older generations of vehicles due to their thick round design. They are typically 3 inches in diameter and are located on the engine's upper side. In these previous models, the EGR valve is operated via a vacuum hose.

A tube connects the upper portion of the EGR to the carburetor. Within the valve is a metal disc that houses a vacuum diaphragm, plunger, and spring assembly.

Electrically Controlled

The majority of manufacturers over the last decade have used an electronic vacuum EGR valve mounted inside a cylinder or, in some cases, a small block. The valve is designed in such a way that it works similarly to the valves installed in earlier models.

It may be imperceptible because, rather than tubes, electronic solenoids are connected to the vacuum lines and the valve as well. This enables the EGR position sensor to connect with the ECU more quickly and efficiently.

How Much Is The Cost of Replacing a Faulty EGR Valve?

Costs for replacement can exceed $500, including parts and labor. Though this can be as little as $150, based on the specific model and brand of your vehicle. On the other hand, if the EGR valve is simply clogged and remains open or closed due to soot particles, it may simply require cleaning.

If you're at least somewhat relaxed under the hood, you should be able to perform this task at home using only a spray can of EGR valve cleaner. The cleaner should cost around $15 and the part should cost between $70 and $490. Car repair costs can quickly add up, that’s why car owners can save more money by doing simple maintenance services at home.


Perhaps the most critical component of the automobile engine is the exhaust gas recirculation system. If you understand how it works, it will be much easier for you to ensure that it is always kept in good condition, which can result in a plethora of problems. It is therefore critical to keep your EGR valve clean and trouble-free.

For more recommendations on auto repair and maintenance, head over to KeepDriving today!

Social Media Manager Petra ensures the team looks as good online as we do personally, or that's what she says when asked. Aside from maintaining our online presence, she also mentors young professionals through our social media management team.
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