An EGR valve is an exhaust gas recirculation valve. This is a vital part of your car's exhaust system. The purpose of the EGR valve is to reduce the pollutants that are put out from the exhaust of your vehicle in an effort to reduce greenhouse gases and other toxins. In particular, the EGR valve helps reduce something called nitrogen oxides. Your car engine is designed to burn very hot, round to 2,500 degrees Fahrenheit. When your engine starts burning hotter than that it can produce a by-product called nitrogen oxides.
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Because your engine burns both fuel and air that it pulls in from outside thanks to the engine intake manifold, the combustion reaction mixes nitrogen that is present in the air all around us with the fuel and oxygen required to create combustion and the by-product at high temperatures is nitrogen oxides. These are extremely toxic, and very bad for the environment. The EGR valve exists to stop this reaction from happening at such a high temperature
How Does an EGR Valve Work?
One of the main gases produced by the combustion reaction in your vehicle is carbon dioxide. That's the same gas that we exhale when we breathe, and the same gas that plants use to produce oxygen through the process of photosynthesis.
Carbon dioxide does not burn so when your engine starts getting too hot, the EGR valve can recirculate carbon dioxide back into the combustion chamber. This suppresses the combustion reaction enough to reduce the temperature. When it reduces the temperature, it won't burn hot enough to produce nitrogen oxide.
Unfortunately, there are times when your EGR valve does not work. If it's not able to recirculate the CO2, then the CO2 will be expelled in your exhaust, your engine will get too hot, and that in turn will create nitrogen oxides as well that end up being expelled in your exhaust.
When your engine is not burning fuel at the correct temperature not only do you have to worry about pollutants, but you're also running your engine too hot which can cause a series of other problems as well. An overheating engine can lead to serious engine damage and end up causing metal to warp as a result. That's an extreme end result, but it's also one that brings with it a price tag that can get up to around $4,000 worth of repairs. Definitely something you want to avoid if at all possible.
When your EGR valve isn't working correctly any longer there are a few signs that you could be on the lookout for it to let you know there is a problem
Signs of a Bad EGR Valve
The way your EGR valve works is that it has ports that allow gases to pass through. When it gets clogged with dirt, debris, or carbon buildup from all the gases that pass through it, it can end up not working effectively any longer. When that happens, you'll probably notice one or more of these symptoms occurring in your vehicle
The Smell of Gasoline: When your EGR valve is malfunctioning, your car will start burning excess fuel as a result of the fuel-air mixture not being what it's supposed to be. When you start burning extra gas, that gasoline can sometimes get through the reaction unburnt and into your exhaust. At high levels you're going to notice the smell of gasoline even inside the cabin of your vehicle. This has a number of dangerous side effects that you're going to want to avoid.
To start with there is the obvious fact that you are now wasting gasoline. That's going to cost you more of the pumps to keep refilling as the gas is not being burned at the correct ratio.
Another problem here is the fumes themselves. It's dangerous to be breathing in gasoline fumes on a regular basis. Excessive exposure to the smell of gasoline can leave you feeling nauseous and light-headed. If it's bad enough you can find yourself getting dizzy behind the wheel of the car and that could be extremely dangerous for you and other drivers on the road. This is one of the most extreme side effects of a problem with your EGR valve, but one of the most noticeable as well. If you could smell gasoline in the cabin of your vehicle, get yourself to a mechanic as soon as you can to find out what the problem is to avoid any potential Danger.
Poor Performance: Because the EGR valve isn't mixing CO2 into the combustion reaction it's likely that your engine performance is going to dip as a result. You're going to have a lower power output and reduce the acceleration. Either from the fuel mix being too lean to have the correct kind of combustion reaction, or even because it's not burning hot enough, or the combustion reaction is occurring at the wrong time because the valve isn't releasing CO2 exactly what it needs to. Any of these things can throw off the fuel-air ratio and cause the engine to perform more poorly than it should.
Rough Idling: If you find that your car is vibrating and shaking a lot even when you're just sitting still with the engine running, that could be a result of the EGR valve being stuck open, closed or just clogged with residue. The gases aren't able to escape the way they're supposed to, and that means they could be backing up into your engine causing potential misfires and other performance problems.
Poor Emission Test Results: A good sign that your EGR valve is not working properly is if you go in for an emissions test and it shows that you have nitrogen oxides in your exhaust. Not every vehicle is subject to an emissions test, and some states don't require you to do them at all. But if you do live in a state where this is required, you're going to end up failing if your EGR valve is bad. This can mean you're not even allowed to drive your car any longer until you get the problem fixed. That could be a great inconvenience and end up costing you money in fines if you don't get it fixed.
Do I Need to Replace My EGR Valve?
If there is a mechanical problem with your EGR valve, then you're going to need to replace the part with a new one. Fortunately, there is an alternative to actually going out and buying a brand-new valve. In many cases the problem with your EGR valve isn't that it's broken, it's that it's so dirty and clogged it can't function properly. That means you can clean the valve and get it up and running again as good as new, or at least pretty close to it.
Cleaning your EGR valve is a good way to greatly improve the performance of your engine if you found that your car is not operating up to snuff any longer. And, if you catch it early enough, it is going to replace some of those serious problems we mentioned and save you money on repair bills in the long run.
Because the EGR valve pulls in exhaust as part of its normal functioning, it's subject to getting a buildup of carbon from the exhaust gases. Over a long enough period of time these can prevent it from working entirely.
When Should I Clean My EGR Valve?
Cleaning the EGR valve in your vehicle is actually a routine maintenance item just like replacing a timing belt or changing an oil filter. Most manufacturers recommend getting your EGR valve looked at and cleaned every 50,000 miles or so. On the bright side, you don't actually need to go into the shop to get this job done. You could clean your own EGR valve at home.
How to Clean an EGR Valve
Your EGR valve is going to be located on the top or the side of your engine. It's possible that it will be obstructed from you by other components, but it shouldn't be too hard to find. The best thing to do is look up your exact make and model of vehicle so you can track down where you need to go to find your EGR valve. On older vehicles it will look like a round metal disc that's about 3 inches across. There's also a vacuum hose connector to the top of it.
In newer cars an EGR valve will have a sensor on top and will appear as a small box, a cylinder, or a block with the valve attached to it as well as sensors and some kind of electrical harness. Again, it's best to look up the precise one for your make and model so you know exactly what it is since there is such a great variation from one car model to another.
In general, the EGR valve is going to be around the cylinder head, the intake manifold, the throttle body, or the firewall. You could also look up on a site like Autozone.com to see what the valve for your make and model of car looks like and just take a look under the hood to see where the matching part is.
To clean the valve, you're going to need a hand full of tools to get the job done.
- Ratchet set
- Socket set
- A scraper
- Pipe cleaning wire brush
- Goggles
- Safety gloves
- You may need an adjustable wrench depending on your car
- EGR valve gasket
- Cleaning solution
The process of getting into your EGR valve to clean it is not too complicated and only takes a couple of steps.
- Disconnect the vacuum hose from the valve. While you're there take a look at it to make sure there's no damage to the hose itself. If there is, you should replace that too. Follow the hose all the way back to make sure that nothing else connected is damaged either. This is just a routine inspection but it's a smart thing to do any time you're looking at something under the hood. No sense repairing one part is connected to something else that's damaged.
- Unplug any electrical connectors that are attached to the valve.
- You can now remove the valve mounting bolts with your ratchet set. If you have a pipe that connects the valve to the exhaust manifold, you'll need to remove it at this point as well. This is what the wrench is for.
- Remove the EGR valve and check the gaskets. If the gasket is still in one piece it doesn't show any signs of damage you could still use it after it's cleaned. Otherwise he'll need to use a replacement gasket.
- Make sure you've got goggles for this and some gloves that are meant for auto repair, ideally want to set her acid resistant because you're going to be using a serious cleaner at this point.
- Spray any carbon deposits you see in the EGR valve with your EGR valve cleaner. You can also use a carburetor cleaner for this job. If you get any on the electrical components or hoses or anything that's not made of metal, wipe those off as soon as you can because the cleaner could cause them to degrade fairly quickly.
- You can use your scraper and the pipe cleaning brush to clean off any build-up you see inside and around the edges of your EGR valve. Follow up with a softer brush and then use a rag to wipe everything clean.
- If you have a serious buildup that isn't scraping off, you may have to leave it soaking in the cleaning solution for several minutes. Again, don't let it touch the electronic or plastic parts as it will seriously damage them.
- Once you have everything cleaned and dried off, reapply the gaskets and reassemble the EGR valve.
- Give your car a test drive after everything has been put in place and see if you're noticing any difference in performance. You should definitely have a smoother running engine at this point, I was a bit more pick up.
The Bottom Line
The EGR valve is a part that many drivers don't give a lot of thought to, but clearly it has an important role in the functioning of your engine. It's also important in helping to preserve the environment and for that reason it's worth the time to do some maintenance to keep it running well. Fortunately, this is one of the parts of your car that's pretty easy to maintain on your own. When you have the time, give cleaning your valve a try to see if it fixes any potential problems. If your problems still persist, at least you know the EGR valve has been eliminated as a source of the issue.