An EGR valve, or exhaust gas recirculation valve, is a part of the exhaust system that helps reduce pollutants that are produced by the combustion reaction in your car's engine. When your engine burns fuel, if the temperature gets above 2,500 degrees Fahrenheit it’s going to start producing something called nitrogen oxides. This is a result of your engine intake manifold drawing in air from outside which is actually mostly nitrogen gas. When it burns at that high of a temperature nitrogen oxides are one of the by-products and they are extremely bad for the environment. The EGR valve recirculates exhaust gases back to the combustion chamber to keep the temperature down and prevent the formation of nitrogen oxides. If your EGR valve fails, the cost of getting it repaired could be between $150 and about $700.
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If you go to AutoZone you can see the prices of new EGR valves range from $40 on the low and up to about $500 on the high end. That's why the repair cost differences are so dramatic. The cost of getting it repaired in your car very much depends on the make and model of the car you’re driving. Obviously, mechanics charge different prices for labor as well, so that's going to factor into the overall price that you're looking at paying when you take your vehicle into a mechanic to get your EGR valve replaced.
There's always the option to repair an EGR valve yourself as well, and definitely save yourself a few dollars on the repairs you are confident in working under the hood of your car.
How Does an EGR Valve Work?
When you're burning fuel normally one of the main gases produced in your engine is carbon dioxide. CO2 doesn't actually burn so it is released through your exhaust. Because your engine will start producing dangerous nitrogen oxides at a high temperature, your EGR valve makes good use of that nonflammable carbon dioxide. The EGR valve recirculates the carbon dioxide back into the combustion chamber. Because it can't burn it reduces the overall temperature of the combustion reaction to lower than the temperature needed to produce dangerous nitrogen oxide. The result of which is that your exhaust is much less dangerous than it would be otherwise.
As the name suggests, the EGR valve is just that, a valve. It opens to allow the gas from your exhaust to recirculate back into the engine, and then closes to allow the gas to flow back into your exhaust as normal when necessary. This is all governed by electronic sensors that determine when gas needs to be redirected to the combustion chamber and when they don't. If your EGR valve fails then it will not be redirecting the carbon dioxide to the engine at the correct time, or it won't be redirecting it there at all. Either one of these is going to cause a problem in your engine which can lead to not just more pollutants in your exhaust but potential engine overheating and other damages as well.
What Are the Symptoms of a Failing EGR Valve?
If your EGR valve has begun to fail, there are some definite signs you need to be on the lookout for that will let you know there's a problem that needs to be addressed. Because an EGR valve isn't one hundred percent necessary for your vehicle, many drivers will often let them slide for longer than they should. And it's true you don't need an EGR valve on your car for it to run. In fact, many older vehicles don't have EGR valves at all. But the fact is that they are an important part of the exhaust system and help reduce airborne pollutants.
You may think that your car can't pollute all that much but it's worth remembering that there are nearly 1.5 billion cars out in the world today. If all of them were producing the toxic fumes that are emitted from a car that doesn't have an EGR valve, then we will be dealing with serious smog related issues on a regular basis. Smog is already bad enough in major cities like Los Angeles, we don't want the rest of the country looking like that as well.
One thing to keep in mind is that the EGR valve may just need to be cleaned rather than replaced if you're having a problem with it. Because the EGR valve deals with the exhaust from your vehicle it has the potential to get clogged up and dirty fairly easily. Sometimes scrubbing it clean and replacing it is all that it takes. Still, if you experience any of these symptoms then it's a sign that your valve needs either that good cleaning, or replacement.
Rough Idling
Rough idling is something that can have a number of causes in your car. It's what happens when you are sitting still in your vehicle and it still seems like the car is struggling. There will be a lot of shaking and vibration and potentially noise from the engine as well, as though the vehicle is having difficulty remaining active. If the EGR valve in your vehicle is stuck in the open or closed position, then the exhaust gases from your combustion chamber are going to be in the incorrect proportions as a result. Either one of these is going to throw your engine's performance off and can lead to a situation of rough idling.
Poor Engine Performance
If your EGR valve isn't working the way it's supposed to then it's very likely that the performance from your engine is going to suffer because of it. Your power output will be greatly reduced, and your acceleration will not be up to the level that you used to. When your EGR valve is the cause of this it is because your fuel-air ratio is not properly balanced. If your car is not burning the fuel-air mixture at the right ratio then you're going to have either what is known as too rich or too lean of a fuel mix going on. This can end up causing you to head to the gas station more often because you're burning fuel inconsistently and are going to need to gas up more often.
Gas Smell
If you're noticing the smell of gasoline in the cabin of your vehicle it may be because the EGR valve is no longer working properly. Because your engine will be burning fuel at an incorrect ratio you could be having more gas injected into the combustion chamber than required. That will lead to an increased odor of gasoline in the cabin of your vehicle. This not only means that you are going to be wasting money because you're going through gasoline faster than normal, it's also a health hazard.
Gasoline fumes can lead to dizziness, lightheadedness, headaches and even nausea. If this happens while you're driving, you could potentially cause an accident. gas you should pull over as soon as it's safe for you to do so.
Failed Emissions Test
Not every state requires that you perform an emissions test so this won't be relevant to every driver out there. That said, if you do live in a state that requires you to perform an emissions test on your vehicle and there was a problem with your EGR valve, then you will likely fail your emissions test. Because the EGR valve isn't able to properly recirculate the CO2 back to the combustion chamber of your engine, you will be producing those toxic nitrogen oxides that we mentioned. Because of that when you go to get your car emission tested, you'll find that you may be producing those emissions. You'll have to get your EGR valve fixed or face some fines as a result.
Check Engine Light
There are many problems that can cause the check engine light to appear on your dashboard so it can be difficult to narrow down precisely what happened to that caused it to come on in the first place. If you experience any of the other symptoms, we mentioned along with a check engine light that that's a better indication that your EGR valve is at fault. Otherwise you're going to need to take your vehicle to a mechanic to get it diagnosed to get to the root of why the check engine light came on.
If you don't want to pay to get a diagnostic done on your vehicle when I check engine light comes on, and let's face it many times were tempted to ignore a check engine light because a car can often perform very well for a very long time with that light on, then what you can do is go to amazon.com and pick up an OBD2 scanner. The onboard diagnostic tool is what a mechanic will use to diagnose the problem when you take it into them. You can pick up a new one for between $30 and $40 on Amazon. When you do, you can run a scan yourself and get an error code that will help you better identify why it came out in the first place. In this case, it should direct you to an error code that reads P0401. That's the code for a problem with your EGR valve. If that pops up, then you know the root of the problem.
Is It Bad to Drive with a Bad EGR Valve?
As we have said that is not 100% necessary for the operation of your vehicle however it's not necessarily a good thing to drive with a failing EGR valve. While on older vehicles didn't have EGR valves and can function properly without them, because your vehicle does have an EGR valve it can cause problems when it stops working properly. Not only is the pollution issue one that you need to be concerned with, the fact is that your engine might also overheat as a result.
Because the EGR valve recirculates CO2 to the engine to lower the temperature of the combustion reaction, without an EGR valve in place your combustion reaction can end up getting too hot and there will be nothing to regulate that. The longer your engine operates at a high temperature the more potential damage you could cause as a result. When your engine is running too hot, you run the risk of warped valves and cylinders and damage to things like the cylinder heads. If this gets bad enough in it for long enough timeline you can end up destroying your engine entirely and facing repair bills that are around $3,000 to $4,000 to repair it.
Can I Replace My EGR Valve Myself?
An EGR valve is something you could replace on your own if you're so inclined. The first thing you want to do though is give it a visual inspection to see if all it needs is a good cleaning. You could use some soap and water and a good scrub brush to get it clean if necessary. If cleaning it will not fix the problem then, as we said, you can get a new EGR valve on AutoZone. Just make sure you're finding the precise right valve for your make and model of vehicle.
Replacing an EGR valve is not a beginner repair job but it's not so advanced as to make it impossible as well. If you have no experience doing DIY car repair, you may want to avoid this but if you're comfortable doing basic repairs you might be up to the task. There are videos online you can find like this one that will show you exactly how to replace the EGR valve so that it can save you some time and effort trying to figure it out on your own if you're not sure what to do.
The Bottom Line
Many drivers might be tempted to ignore a problem with your EGR valve since, as we said, it's not essential to the proper functioning of your vehicle. However since it can help reduce overheating of your engine and it's also responsible for preventing the release of numerous pollutants into the atmosphere it's a good idea to get this problem fixed in a reasonable period of time after you first notice it. This is one of the few parts of your car that is in place not just to help you and your driving experience but help other drivers in the world at large. Pollution is a serious issue, just look at some of those images we mentioned of smog hovering over big cities in China or in Los Angeles. The best way to prevent that is to make sure that you're doing your part to keep your car running smoothly and cleanly.