Updated at: 10-08-2023 - By: Lucas

Do you think that your car’s EGR valve is broken? An EGR valve is built into every new car. If it gets clogged or broken, the engine won’t run as well.

Now, if you’re new to cars or don’t play with your toys much, you might not have heard of EGR. Most mechanics may try to take advantage of car owners in this way. But don’t worry, we’ll take care of you.

When the EGR valve is broken, the engine doesn’t run well, the engine check light comes on, the exhaust smells like unburned fuel, the emissions test fails, and the engine runs rough.

How can you tell if your EGR is really broken? and why might this be happening? You’ll also learn everything there is to know about this simple but complicated part of a car, so let’s get started.

5 Symptoms of Bad EGR Valve?

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When the EGR breaks, it can cause a lot of trouble. For example, the fuel economy of the vehicle is hurt, which will cause it to use a lot of fuel, which can lead to carbon deposits, more pollution, broken injectors and sparks, and other problems.

So, if your EGR is broken, you must get it checked as soon as possible. Even though there are many bad signs that your EGR valve needs to be looked at, here are the most important ones.

1) Poor Engine Performance

Bad EGR valves can cause a lot of problems, but the first and perhaps most frustrating one is how the engine runs. When you step on the gas pedal, there is a good chance that you will have trouble getting going or that the engine will have less power overall. This can also happen if the fuel filter isn’t working.

This can happen if the ratio of air to fuel is too rich or too lean[1]. Because of this, the engine may need more gas than usual in almost every driving situation. This will really hurt your wallet, especially since gas prices aren’t going down.

2) The Engine Warning Light

If the EGR valve fails, you should always check the engine indicator, which will usually light up on the dashboard (unless you’ve also damaged it, in which case you’ll also need to replace it).

We won’t get too technical here, but just know that the Engine warning indicator will light up if the ECU detects a problem with the engine or any of the parts that are directly connected to it.

The EGR is directly connected to the engine, so any problems with how it opens, closes, or does other things will be picked up right away by the EGR valve sensors.

3) Smell of Unburnt Fuel

Since the EGR valve isn’t working right, the engine is taking in more fuel than it should, which will cause more hydrocarbons to come out of the tailpipe in the long run. This will make the smell of fuel worse, to the point where you can smell it inside the car if the air conditioner is not set to recirculate.

It can be terrible for your health and is very annoying. Something is definitely wrong with the engine if it does this.

4) Failed Emissions Test

If you have to test for higher levels of emissions every six months, you might have a broken EGR valve. Even though this test might not be a good indicator of how well the EGR is working, if you fail your emission test, it’s a good idea to have a professional check out your vehicle’s EGR valve.

5) Rough Idling

When the EGR valve in the engine is broken, the engine will have a rough idle. So long as the problem isn’t fixed, the valve will stay stuck in either the open or closed position. This could also mean that a little too much exhaust gas is getting into the combustion chamber.

This will mess up the right mix of air and fuel for the engine to run smoothly. Then, you’ll see the rpm needle move around as the car struggles to keep the rpm at idle.

When the EGR valve is stuck open, it lets out vacuum, which makes the engine burn less efficiently. When a valve is stuck in the closed position, it lets out more nitrogen oxide, which throws off the timing of the engine and causes it to knock.

What is an EGR Valve?

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The Exhaust Gas Recirculation valve, or EGR valve, can be found in most modern cars that run on gasoline or diesel. Its job is to help cut down on engine emissions by sending some of the exhaust gas back into the engine.

Over the past few years, it has been shown that pollution has caused big changes in the climate, and that cars are a major cause of this pollution.

In return, the government has given car makers rules to follow, and adding the EGR is one of them. So, almost every car you see on the road today probably has an EGR.

Pros and cons of an EGR valve

With an EGR valve, the temperature in the cylinder will drop by a lot. Without getting too technical, here’s a quick explanation of how engines work: they take in air and mix it with fuel at a certain temperature and pressure. This mixture is then ignited to make energy that moves the wheels of the vehicle.

But this process makes a lot of heat, which is never a good thing. With the help of an EGR valve, some of the exhaust gas is allowed to flow through the inlet manifold, where it replaces some of the oxygen in the air. This keeps the engine cooler and more efficient.

NOx (a pollutant exhaust gas) is mostly made when the temperature is high and there is too much oxygen in the air. And based on what has been said so far, it is clear that an EGR reduces both the amount of excess oxygen and the temperature of the engine.

It also helps cut down on the amount of nitrogen that is released into the air. Exhaust Gas Recirculation (EGR) is one of the simplest methods that can be used to stop NOx from being made.

How does an EGR work?

A lot of air is around us, and the engine’s intake manifold takes it in. About 20% of air is made up of Oxygen and 80% is made up of Nitrogen. There are also some very small amounts of other things, but oxygen and nitrogen are the main ones that react. Find out how to care for Turbocharged Engine.

What does an EGR valve do? At high temperatures (around 25000F inside the engine), while the oxygen reacts with the fuel, the nitrogen burns to make more NOx emissions. In this case, the EGR’s job is to send the gases that are being released back into the combustion chamber. This lowers the temperature and almost completely stops NOx from being made.

EGR System Tech Evolved Overtime

Different kinds of EGR valves are used in the engines of modern diesel and gasoline cars. Before you learn what causes EGR problems, it would be best to know what kind of EGR your car has. This will make it easier to figure out what the problem is.

Old vehicle models

In older cars, the thick, round shape of the EGR valves meant that they took up more space. Most of the time, they are 3 inches in diameter and are on the top of the engine.

On these older models, the EGR valve is controlled by a vacuum hose. The upper part of the EGR and the carburetor are connected by a tube. The metal disc is inside the valve, which is made up of a vacuum diaphragm, plunger, and spring.

Semi modern vehicle models

In the last ten years, most manufacturers have put an electronic vacuum EGR valve inside a cylinder or a small block. The valve is made so that it works the same way as the ones that came with the older models.

It can go unnoticed because electronic solenoids are connected to the vacuum lines and the valve instead of tubes. This makes it easier and faster for the EGR position sensor to talk to the ECU.

Newer models

In modern cars, the EGR setup is similar to the above-mentioned tool, but the vacuum control lines have been replaced by a digital valve, which improves performance and reliability by a large amount.

Radical design

On many other models, the EGR valves have been replaced with EGR jets, which take in a smaller amount of the exhaust. They can be found in future car models, but you probably won’t see them very often. Some high-efficiency engines, such as those with variable valve timing, don’t need EGR at all.

Important Tip: It’s also important to know what kind of EGR your car has. Most of the time, your mechanic will tell you this, but if you ever need to buy a replacement on your own, know that there are five types of EGR valves that are easy to tell apart: Back Pressure EGR valves, Vacuum controlled valves, Electronic vacuum control EGR valves, EGR jets, and Digital EGR valves.

Three EGR Valve Faults:

There are only 3 different kinds of bad EGR valves, and they all have different signs. Two different things can go wrong with the EGR valve. It can either always stay closed or always stay open.

Because of all the carbon deposits that haven’t been burned, it can also get stuck when it’s not moving. So let’s talk about these hard cases and figure out how to diagnose them.

1) When the EGR valve is stuck open

When the EGR valve is open, there is a chance that it will let air out of the engine. This leak will lead to incomplete combustion, which is usually what causes rough starting and the rpm needle to jump around.

How to figure out why the EGR won’t close

When the car is parked in the “idle” position, you need to look for a plunger shaft and check the position of the valve with your hands. If that isn’t an option, there are a few On-Board Diagnostics (OBD) devices that can be plugged into the car and checked for problems (more on this later).

When the valve is stuck in the open position, error codes like P1406 and P1404[2] can be seen. Then you would have to take out the plug and use a carbon cleaner to fill the empty spaces.

In other cases, if the working fluid inside the EGR leaks when the world is turned upside down or when it is held open, all you have to do is use a valve cleaning kit and then pull the vacuum from the valve.

2) When the EGR is stuck closed

As we’ve already talked about, if the EGR is in the closed position and stays there, a lot of NOx will be released. This type of car could even make knocks[3]. This will throw off the timing of the engine in a different way and cause it to wear out more quickly. This is not something we want at all.

How to figure out why an EGR valve won’t open:

If the car revs up while it’s parked, you should always check the moving EGR valve. When the EGR is stuck closed, the OBD ECU scan tool may show errors P041 and P1406.

If you hear a knocking sound, it could mean that the valve has already been turned off. You’ll have to take the valve off by hand. At this point, you’ll need a valve kit. If you don’t want to get your hands dirty, you can always go to your mechanic.

3) Clogged EGR valve

Carbon that hasn’t been burned can also keep the EGR valves from staying in the right place. This kind of problem can make the engine run rough. This can only happen when the car is in its start position and the situation is very bad. When EGR valves get clogged, exhaust gas can’t be recycled. This usually happens after a car goes 30 mph (45kmph).

Diagnose and fix an EGR that is clogged

The ECU scan tool shows errors P1404 and P1406 when the EGR valve is blocked. Just take off the valve and clean it with a valve cleaning kit or throttle body cleaner to get rid of the dirt.

If you don’t know how to fix the problem or can’t get the right tools, you should probably call a mechanic.

A smog test is also a good way to find an EGR valve that is clogged.

If the EGR valve gets clogged or shut off completely, it can’t burn harmful emissions inside the combustion chamber again. NOx emissions will flow through the combustion chamber and out the exhaust pipe without being controlled.

During a smog test, the high NOx emissions will show up and cause the car to fail. In addition to releasing NOx, a clogged EGR could make the fuel mixture richer and cause too much HC (hydrocarbons) and CO to be made (carbon monoxide).

Check Engine Light for Diagnosis

If the EGR valve is clogged or broken, the “Check Engine” or “Emission Control” light will come on. The owner will have to take his car to a certified test and repair centre with a code scanner (OBD diagnostic tool).

The scanner will then be connected to the computer system of the car, and a trouble code will be found. If the system fails because of the EGR valve, the code number will tell you that the EGR is the part that failed.

When the EGR fails and the engine overheats, more lubricating oil might get into the combustion chamber. If this happens, the diesel engine might start running on lubricating oil even if the fuel supply runs out. Then, a diesel engine might start to run on oil instead of fuel.

The driver might not be able to turn off the engine any other way than to force it to stop. At some point, the engine will use up all of the oil that keeps it running smoothly, and the engine might break down.

Cost of Repairing/Replacing EGR Valve

Most problems with the EGR valve can be fixed by using a throttle body cleaner to clean it. If you clean out the built-up carbon, it should work better and not get stuck in the open or closed position. For this 20-minute job, you’ll need some muscle and a throttle body cleaner.

Depending on what kind of car you have, replacing the EGR valve can cost anywhere from $40 to $800. (Check exact price on Autozone.com). The cost of installing something should be around $70.

Safety Tips:

Most mechanics should be able to replace an EGR without too much trouble because it doesn’t usually require a lot of technical know-how. But if you find yourself in a situation where you have to do it yourself, make sure you take all the right steps to keep yourself safe.

Taking pictures of the engine bay and the connections from the EGR valve is a good idea.

Let the EGR cooler cool off, and then disconnect it from the battery. You will have to wait a few minutes for the electrical system to be completely discharged. If you don’t, you might get a small shock or even hurt the battery.

To keep the shorting from happening, the battery terminals should be disconnected (Remove negative terminal first, then positive to prevent chances of short-circuiting but accidentally touching positive terminal to chassis). But before you take anything off, you should make sure that the replacement EGR valve you bought works. Most EGR valves are set up the same way, so it may look the same as the old one. It may even have the same connections and fittings. Make sure the part number is the same.

There may also be vacuum pipes attached to the EGR valve. Be sure to label the pipes before you twist and pull them off with brute force. Most manufacturers already put labels on them, but if you don’t see one, put one on.

Make sure you don’t break them or stretch them too much. If they are broken or cracked, you need to make sure you replace them with newer ones. Even though these pipes aren’t that rare or expensive, it’s best to get new ones.

Once you’re done, you have to carefully remove any wires that go to them. This is easy to do with your hands, since most of them are just tightened by hand.

The valve can be attached to the cylinder head with bolts and have a strong outer body. Because it always has hot gases from the engine going through it. Because of this, the bolt that holds the valve may end up being very tight. Before you do this, it might be a good idea to spread it with something like WD40 and let it sit for a few minutes.

Once you’ve cleaned all the bolts with the degreaser, use force to pull the valve and body out with your hands. There is a chance that the valve will get stuck, but if you push and pull on it, it should come off.

Then, you have to carefully remove any old gasket pieces from between the valve body and the cylinder head and clean the area, trying not to let any dirt fall into the cylinder head.

The old gasket should then be taken off and a new one put in its place. The new gasket and valves should be put together. A good idea would be to use a small amount of silicone sealant that can handle high temperatures.

To put the valve back in the engine, you just have to do everything backward. Before you start the car and go for a drive, you may need to reset the engine check light and make sure it idles smoothly.

Some Final Thoughts

The exhaust gas recirculation system might be the most important part of the car engine. If you know how it works, it will be easy to keep it in good shape. If it’s not in good shape, it can cause a lot of problems, so it’s important to keep your EGR valve clean and free of problems.

Frequently Asked Questions

Even if the EGR valve has broken, the car can still be driven for the most part. But it won’t work well. You might notice that the engine isn’t running well, that the engine check light is on, that the exhaust smells like unburned fuel, that the emissions test failed, and that the car is hard to start.

Yes, most problems with the EGR can be fixed by using throttle body cleaner to clean the valve well. The EGR unit doesn’t usually need to be replaced.

A valve that lets exhaust gas go back into the engine helps cut down on emissions. When the engine is too hot and there is too much oxygen in the combustion chamber, the engine lets out too much NOx, which is a harmful gas. Some of the exhaust gas is sent back into the combustion chamber through the EGR valve. This takes away some of the oxygen and lowers the temperature of the engine. This makes less NOx gas go into the air.