The exhaust gas recirculation valve is an inconspicuous component in the intake tract of many diesel engines and some petrol engines. It ensures that a certain amount of exhaust gases is fed back into the combustion chamber. A defective EGR valve can worsen the exhaust gas values and limit the function of the engine. If symptoms of a defect appear, you should take action. Often, cleaning the EGR valve is enough to prevent engine problems.

Function of the EGR valve in the car

The EGR valve is an important component of the external exhaust gas recirculation of modern combustion engines. With its help, exhaust gases are guided from the engine’s exhaust back into the intake tract. This primarily improves the exhaust gas values of the vehicle.

For this purpose, the EGR valve merely diverts part of the exhaust gases produced during combustion upstream of the exhaust system. The amount is determined by the car’s engine control system. Depending on requirements, the valve is then either opened further or closed.

Position and design of EGR valves

Most EGR valves on passenger cars are controlled either pneumatically or by means of electromechanics and a servomotor. The valves have a valve chamber through which the exhaust gas is passed. A slide or poppet valve inside regulates the flow of exhaust gas.

The exhaust gas recirculation valve is located in the engine compartment close to the engine. Depending on the model, it can be installed directly on the exhaust manifold, or it can be found closer to the intake tract. Often the EGR valve is combined with an EGR cooler, which cools down the exhaust gases before recirculation.

This is what the EGR valve does in the combustion engine

EGR valves are primarily installed in modern diesels, but can also be found in petrol cars. In cars with diesel engines, this type of exhaust gas recirculation lowers the combustion temperature in the cylinders by several hundred degrees Celsius.

The lowered temperature of diesel reduces the emission of harmful nitrogen oxides. These are produced in the combustion chamber primarily at high temperature and pressure. The emission of soot is also reduced in the compression-ignition engine. With petrol engines, on the other hand, exhaust gas recirculation primarily reduces fuel consumption.

EGR valve or EGR valve – what is the difference?

The various designations of the exhaust gas recirculation valve sometimes cause confusion. However, it is usually one and the same component. The second term is simply the abbreviation of the English term Exhaust Gas Recirculation. AGR, on the other hand, is the German abbreviation for exhaust gas recirculation.

EGR valve defective Symptoms

If the EGR valve is defective, the engine and exhaust gas cleaning system can no longer work optimally. This is due, among other things, to the fact that exhaust gases are only fed to the engine in the partial load range. Defects in the EGR valve such as a failure or jamming can lead to the following symptoms:

• Engine does not run smoothly and jerks
• Speed fluctuates
• Emission values are poor
• Fuel consumption is increased
• Power loss at full load
• engine control light is lit

If there is a defect in the EGR valve, it can get stuck in the open or closed state. This means that exhaust gas is sometimes supplied to the engine even though this is not intended by the engine management system. The exhaust gas flow can also be blocked incorrectly.

These symptoms occur

If the EGR valve is defective and permanently open, too much exhaust gas is fed into the engine, for example, at full load. This means that the engine lacks fresh air, so that optimal combustion is no longer possible. The result is a loss of power.

If, on the other hand, the valve is jammed when closed, the exhaust emission values, among other things, will deteriorate. In this case, the car cannot pass the emissions test. A defective EGR valve can also cause symptoms such as engine judder, fluctuating engine speeds or increased fuel consumption. The check engine light may also light up if the EGR valve is defective.

Causes for a defective EGR valve

A fault in the exhaust gas recirculation valve can have several causes. The first symptoms often occur when the valve becomes jammed due to dirt. Sometimes the blockage is cleared at first, only later is the EGR valve completely defective or permanently jammed.

• EGR valve is dirty
• Connection on EGR valve is defective
• Pneumatics for EGR valve does not work
• Software for engine control was changed

A common cause of problems with the exhaust gas recirculation valve is contamination of the component. The actuating mechanisms inside the valve chambers are located directly in the exhaust gas flow, and are thus exposed to numerous stresses. Above all, soot and oil residues in the exhaust gases can contaminate and block the EGR valve.

Other possible causes are

The EGR valve itself is not always the cause of problems in the area of exhaust gas recirculation. A faulty connection on the electrical EGR valve can also be responsible for the malfunction. The same applies to defects in the pneumatics of pneumatically controlled EGR valves. Also, the software of some diesel vehicles has been modified in such a way that more exhaust gases are recirculated. This causes the EGR valve to wear out and become dirty more quickly.

Clean the EGR valve

If there are clear symptoms of a fault in the EGR valve, then the component should be checked. In many cases, cleaning the exhaust gas recirculation valve is sufficient to restore the function. It is not always necessary to replace the EGR valve.

For thorough cleaning, professionals usually remove the EGR valve. Although some manufacturers offer sprays that are supposed to clean the EGR valve even when it is installed, cleaning it when it is removed is usually more thorough.

Cleaning the EGR valve in 5 steps

1. Locate EGR valve: First locate the EGR valve in the engine compartment. It is usually a large metallic component. A repair manual can answer questions about the location of the EGR valve.
2. Remove the valve: Once the EGR valve has been found, it is removed. The procedure may differ depending on the vehicle model. The electrical and pneumatic connections are loosened first. Then the screws can be loosened and the EGR valve removed.
3. Check EGR valve: After removing the exhaust gas recirculation valve, it is visually checked for damage. If parts inside are broken or defective, the only solution is to replace it with a new EGR valve. Contamination, on the other hand, can be easily removed.
4. Cleaning the valve: In most cases, the EGR valve is heavily contaminated with exhaust residues. To clean it, spray a special EGR valve cleaner from the trade into the component. After a certain amount of time, the dirt can be removed with a soft cloth.
5. Install the EGR valve: After cleaning and checking, the EGR valve can be reinstalled in the car. This is done in the reverse order to disassembly. All connections and hoses are put back on the EGR valve, followed by a test run.

Changing the EGR valve

If the EGR valve is defective and does not function even after cleaning, replacement with a spare part is unavoidable. Repairs to the component itself are usually not possible. The exhaust gas recirculation valve is replaced in a similar sequence to cleaning.

As a new part directly from the manufacturer, an EGR valve can cost several hundred euros. It is sometimes cheaper to install a good used spare part. At Autoparts24 you can find exhaust gas recirculation valves and EGR coolers for many vehicle models. Shipping is always free of charge.