Bad EGR Valve: Signs, Symptoms, and Replacement Cost

An EGR valve is a crucial component that helps prevent excessive pollution from exhaust gasses and helps combustion chamber temperatures. Though it is a simple component, an EGR valve failure can have some serious implications when it comes to engine performance.

Symptoms of a bad EGR valve include rough idling, excess exhaust odor, decreased engine performance, a failed emissions test, and the illumination of the check engine light.

What Is an EGR Valve?

egr valve

An EGR valve, or exhaust gas recirculation valve, is a device that recirculates dangerous exhaust gasses from the combustion chamber back through the intake manifold and into the combustion chamber again. The result of this is that harmful nitrous oxides are reduced as the air and fuel mixture combusts and the temperatures of combustion are lowered. 

Both of these are important for emissions and optimal running of the engine, and the valve operates differently depending on the conditions. It opens and closes based on when and how the engine is running; thus, continuously controlling the number of gasses that recirculate through the engine, further helping it run correctly.

Common Signs and Symptoms of a Bad EGR Valve

Many of the signs and symptoms of EGR valve failure are similar to those presented by bad spark plugs, a leaking or broken cooling system, and air filter issues. A good way to isolate EGR issues is to address these other components first, all of which are usually easy to access. 

Excess Exhaust Odor

One of the telltale signs of an EGR valve issue is the smell of gasoline, especially within the cabin of the vehicle. It can be normal to smell a little exhaust if you stand behind a vehicle when it is running since you would be in the direct line of fire, but when exhaust fumes start to permeate other areas in and around the vehicle, it means that too high of a concentration of hydrocarbons is being released into the exhaust system and out of the tailpipe.

This usually occurs when the EGR valve fails to open, not allowing necessary recirculation to occur.  

Decreased Engine Performance

When the EGR valve functions properly and can control the amount of recirculated exhaust gasses back into the engine with incoming clean air, the computer will be able to adjust the air and fuel ratio to keep the engine functioning normally. If there is too much exhaust gas that re-enters the combustion chamber, the vehicle’s computer cannot always compensate enough.

The result is that acceleration and driving at speed can be hampered by the incorrect air and fuel ratio. This often occurs if the EGR valve gets stuck in the open position, allowing the free flow of exhaust gas back into the engine.

Rough Idle

For the same reasons mentioned above, rough idling can occur from incorrect air and fuel mixing within the combustion chamber. Although this can affect acceleration and normal driving, it is usually more evident at idle since the engine is already running slower. The slower the engine runs, the more difficult it can be to keep it running at all when the engine is essentially choking itself out.

Engine Stalling

Engine stalling is one of the worst-case scenario events that can happen when you have a bad EGR valve, but as mentioned above, this is more likely to occur at idle than when driving at speed. There will most likely be many other symptoms of EGR valve failure before it gets to the point where stalling occurs, so it is important to not ignore problematic symptoms when they present themselves. 

Decreased Fuel Economy

Anything that causes the engine to run poorly will almost always have the potential to affect fuel economy negatively. Engines are designed to work in time and cooperation with each component, and whenever it is forced to work overtime to compensate for the failure of a certain component, fuel consumption usually goes up. 

Decreased fuel economy can be a symptom of several different component problems, so it should be treated as a supplementary symptom of an EGR valve failure if other EGR-related symptoms present themselves. 

Failed Emission Test

Because the EGR valve is a part of the emissions system in a vehicle, just about any vehicle with a bad valve will signal a red flag during an emissions test, and the vehicle will fail. This is potentially a good indicator that the EGR valve is bad, especially if no other obvious signs are present. Unfortunately, not all areas require emissions testing, so this is not always a surefire way to diagnose an EGR issue.

Learn More: Bad Oxygen (O2) Sensor Symptoms

Check Engine Light

Your vehicle is full of sensors and wiring that can cause the check engine light to come on. The EGR valve can trigger the check engine light if the circuit is bad or if the position sensor fails. Although the check engine light is useful, it can be caused by a host of different issues. To see what the fault code is, you can usually take your vehicle to an automotive retail location for a free OBD scan or source one yourself.

What is the Expected Lifetime of an EGR Valve?

old egr valve

Most EGR valves can last for over 100,000 miles if the vehicle is taken care of. Sometimes, due to poor maintenance or engineering flaws, their lifespan can be decreased depending on the severity of factors at play. The most common issue that causes EGR valves to fail prematurely is carbon buildup that causes them to stick open, fail to close, or clogs them. 

It is quite rare that an EGR valve needs to be replaced more than once over the lifetime of ownership of a single vehicle. It is also rare that a clogged EGR valve is recommended to be cleaned out rather than replaced. Cleaning a clogged valve can be done, but the chances that a negative effect on the emissions system is lower if the entire valve is simply replaced rather than cleaned and returned to service. 

How Much Does an EGR Valve Cost to Replace?

An EGR valve replacement does not usually cost as much as other major engine components. Inexpensive parts can cost as little as around $100 with low labor costs of around $50. More expensive parts can cost as much as $400 with more involved labor costs of up to $120. 

This is all dependent on the make and model of the vehicle, as well as the amount of equipment and components that need to be removed to access the valve. The most expensive EGR valve jobs can cost well over $500 when all is said and done, but most replacement costs for parts and labor fall around $250 to $300.

Final Thoughts

The EGR valve is an important part of the emissions system of your vehicle. Not only does it recirculate exhaust gasses back through the intake manifold and into the engine, but it also keeps combustion temperatures cooler, neutralizing some of the harmful nitrous oxides produced by combustion. If the valve fails, your vehicle can idle roughly, experience decreased performance, fail an emission test, and the check engine light could come on. 

Richard Reed
I've been a General Manager of a moving company and I've also been a Professional Mover for over 30 years. I've driven flat beds, reefers, dropdecks, moving vans, heavy machinery, etc. In my time as a Mover I've driven over 1,000,000 safe miles. My days of moving and driving truck are past me but The Vehicle Lab allows me to share the knowledge I've gained over the past 40 years.
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