How to replace the exhaust gas recirculation (EGR) valve

Your vehicle may display a Check Engine light, may not operate properly, or may not pass a local emissions test. These can be some of the common symptoms of a failed EGR (exhaust gas recirculation) valve. EGR not only directly affects your vehicle's emissions, but it can also cause more severe handling problems for your vehicle. Knowing what an EGR valve does and how to diagnose it can help you save some money by doing the repair yourself, or at the very least help you become an informed consumer.

Part 1 of 3: Understanding the purpose of the EGR valve and how it works

The EGR valve or EGR valve is part of your vehicle's exhaust system. Its main purpose is to reduce the NOX (oxide of nitrogen) emissions your engine emits. This is achieved by recirculating the exhaust gases back to the engine, which stabilizes the temperature of the combustion chamber, and also allows the combustion process to start again on the exhaust gas recirculation, which reduces the amount of unburned fuel in it.

There are two types of EGR valves, electronic and manual. The electronic version contains a solenoid that allows the computer to open and close it when needed. The manual version opens when the engine vacuum is applied to it, then closes when it releases the vacuum. Regardless of which one you have, the operation of the system is the same. The vehicle's computer will control the opening and closing of the EGR valve based on vehicle speed and engine temperature.

On most vehicles, the EGR valve will only be applied when the engine is warmed up to normal operating temperature and the vehicle is moving at highway speed. When the system is not working properly, it can lead to something as simple as the Check Engine light coming on, to something as serious as stopping the engine.

Part 2 of 3: Diagnosing a Faulty EGR Valve

The EGR valve can fail for various reasons. When this happens, it can cause a range of symptoms. When an EGR valve fails, it usually fails in one of two ways: it either gets stuck open or it gets stuck closed. These symptoms can be very similar to other car problems, so proper diagnosis is essential.

Check if the engine light is onA: When the EGR valve fails, it may cause the Check Engine light to come on. If the light is on, the computer needs to be scanned for codes. If there is an EGR low flow code, it means that the EGR valve is not opening.

The computer can tell if the EGR valve is opening by the changes it sees in the oxygen sensors when the valve is open. You may also receive an incorrect voltage code for the EGR valve, which may indicate a circuit problem or valve failure. A lean mixture code may also appear if the EGR valve is stuck open. If the EGR valve is stuck open, unused air will enter the engine, causing the computer to see too much air in the engine.

Rough idle: If the EGR valve is stuck in the open position, it will cause a vacuum leak. This will result in the engine idling intermittently because the computer will not be able to correctly detect excess air.

If any of these symptoms appear, the valve should be diagnosed. Depending on the type of vehicle, it will be determined how it will be checked.

EGR Missing/Low Flow Code: This means that there is not enough exhaust gas entering the engine when the EGR valve is opened. This may be due to a number of reasons. The ability to diagnose each of them will help you find the problem.

• Electronic EGR valve: The EGR valve may be defective or have a control circuit malfunction. The best way to diagnose this is with a scanner first. With the engine running, the EGR valve can be opened and closed, and you can monitor its correct operation. If it does not work, then you need to check the EGR valve with an ohmmeter. If the valve experiences poor results, it must be replaced. If everything is in order, the circuit must be checked with a voltmeter.

• Manual EGR valve: Manual EGR valve or its control solenoid or circuit failure may be present. The EGR valve can be checked with a vacuum pump to see if it is stuck in the closed position. With the engine running, you can use a vacuum pump to apply vacuum to the EGR valve. If the engine idle changes when vacuum is applied, the valve is good. If not, then it needs to be replaced. If the EGR valve is OK, check its control circuit and solenoid.

• Clogged EGR channels: The EGR valve may also be good when you get a flow problem code. The EGR passages that connect the exhaust to the intake are often clogged with carbon buildup. Usually the EGR valve can be removed and the passages checked for deposits. If there is accumulation, then it must first be removed and then re-test the car.

If the problem with the car is due to a lean code or an idle problem, this indicates that the valve is not closing. The valve must be removed and the internal components can be checked to see if they move freely. If not, then it needs to be replaced.

Part 3 of 3: EGR valve replacement

Once the valve has been found to be defective, it must be replaced.

Necessary materials

• EGR valve
• Ratchet with sockets
• Wrench (adjustable)

Step 1: Park your car on a level surface.. Park on a level surface and apply the parking brake. Let the engine cool down.

Step 2: Locate the EGR valve. The EGR valve is usually located on the intake manifold. An emissions sticker under the hood can help you find the valve.

Step 3: Loosen the exhaust pipe. Use a wrench to loosen the exhaust pipe attached to the EGR valve.

Step 4: Remove the bolts. Using a ratchet and appropriate socket, remove the bolts holding the valve to the intake manifold and remove the valve.

Step 5: Install the new valve. Install the new valve in reverse order and tighten its mounting bolts to manufacturer's specifications.

After installing a new EGR valve, it can be checked again. If checking and replacing the EGR valve seems too difficult for you, you should seek the help of a certified mechanic who can replace the EGR valve for you.