EGR Valve replacement & repair made easy

How does an EGR valve work?

In simple terms, the EGR valve helps your car run cleaner by sending some exhaust gases back into the engine to reduce pollution.
Here's how it works: The EGR valve takes some of the exhaust gases (the stuff that comes out of the engine after fuel is burned) and sends them back into the engine.
These exhaust gases mix with the fresh air coming into the engine. This mixture lowers the temperature of the combustion process (the burning of fuel and air). Some EGR units have a cooler as part of them, that is plumbed into the engine’s cooling system, literally to cool the exhaust gasses before they go back through.
By lowering the temperature, the EGR valve helps reduce the formation of harmful nitrogen oxides (NOx) in the exhaust. NOx is a major pollutant that contributes to smog and air pollution. The EGR valve opens and closes at the right times to control how much exhaust gas is recirculated. It opens when the engine is warm and under certain conditions (like cruising on the highway) and closes when it’s not needed (like when the engine is cold or at full throttle).

What does an EGR valve replacement job involve?

An EGR valve replacement job involves several key steps to ensure your car's exhaust gas recirculation system functions properly again.

• The mechanic will physically inspect the area around the EGR valve for leaks
• A full diagnostic test will be carried out with monitoring of live data. If deemed to be faulty and once the engine has cooled, the EGR valve will need to be removed and replaced
• The battery is disconnected to prevent any electrical shorts or accidents while working on the EGR valve.
• The mechanic locates the EGR valve, which is usually mounted on or near the intake manifold. Any components obstructing access, such as the air intake duct or engine cover, may need to be removed.
• Next, the mechanic disconnects the vacuum lines, electrical connectors, and any other hoses attached to the EGR valve.
• The old EGR valve is unbolted and removed from its mounting position on the engine.
• The mechanic inspects the EGR passages and cleans any carbon buildup or debris to ensure proper flow and function of the new valve.
• The new EGR valve is then positioned and bolted into place, ensuring it is securely mounted.
• The vacuum lines, electrical connectors, and any other hoses are reconnected to the new EGR valve, making sure all connections are secure and free of leaks.
• Any components that were removed earlier to access the EGR valve are reinstalled.
• The battery is reconnected, and the mechanic starts the car to test the new EGR valve. They check for proper operation and ensure there are no error codes or warning lights on the dashboard.
• Vehicle is road tested

This job requires skill and precision, which is why it’s best done by a professional mechanic.

How do I know whether I need an EGR repair or replacement?

If your check engine light comes on, it could indicate a problem with the EGR valve. Look out for these key signs and symptoms:

• If your engine performance is poor, such as reduced power, acceleration, or fuel efficiency, it could be due to a malfunctioning EGR valve. This happens because the EGR valve isn’t regulating the flow of exhaust gases properly.
• If your engine idles roughly or stalls frequently, it might mean the EGR valve is stuck open or closed. This improper function can disrupt the air-fuel mixture in the engine.
• If you fail an emissions test or notice increased emissions, it could be a sign that the EGR valve is faulty. A malfunctioning EGR valve can lead to higher levels of nitrogen oxides (NOx), causing your vehicle to emit more pollutants.
• If you hear knocking or pinging sounds from the engine, it could be due to an issue with the EGR valve. This noise can result from improper combustion of the air-fuel mixture in the engine, which the EGR valve helps regulate.
• If you see excessive soot or carbon buildup around the EGR valve and its passages, it might be clogged. This buildup can restrict the flow of exhaust gases, necessitating cleaning or replacement of the valve.

Can I fix EGR valve issues myself?

The most common issue with EGR valves is blockage caused by the buildup of carbon deposits, soot particles, and dirt, leading to the valve and passages being completely clogged.

You can attempt to fix EGR valve issues yourself without removing it, particularly if the problem is caused by a blockage of carbon deposits, soot particles, and dirt. One common DIY method is to rev the engine to high RPMs, which can help blow out the accumulated soot and carbon, temporarily stopping gas recirculation and cleaning the valve.

However, if the blockage is severe or if you're not confident in performing this maintenance, it's advisable to consult a professional mechanic for a thorough inspection and repair.

What sensor controls the EGR valve?

The EGR valve is typically controlled by the EGR valve position sensor, which is part of the EGR system in many modern vehicles. This sensor monitors the position of the EGR valve and sends feedback to the engine control unit (ECU) to ensure the valve operates correctly.

Additionally, the ECU uses data from other sensors, such as the mass airflow sensor (MAF), manifold absolute pressure sensor (MAP), and oxygen sensors (O2 sensors), to determine when and how much the EGR valve should open or close. These sensors help the ECU regulate the flow of exhaust gases recirculated back into the engine, optimising combustion efficiency and reducing emissions.

If this sensor is faulty it may trigger the engine management light on the dashboard and other related symptoms and will need to be checked and replaced if necessary.

Physically cleaning of EGR valve instead of replacement

In theory yes it’s possible to physically clean it, in practical terms though it isn’t always worth it. Some EGR valves can take 5-6 hours to remove and refit, so if you then add in the cleaning time of around 2 hours, the labour costs are sky-high. Then, if it doesn’t work, or if it fails again shortly afterwards, then you are in the same situation again with another serious labour cost plus the part.

Therefore unless it's really quick to remove (and some are!) and the parts are inexpensive, it is worth trying, otherwise, it doesn’t make sense long term.

Should I use an EGR cleaning additive in my fuel?

Common sense dictates that the more efficient an engine is running, the cleaner the exhaust gasses will be. Using so-called EGR system cleaners that simply get poured into the fuel tank, will not directly clean the EGR valve, a cleaner running engine = less deposits so less chance of it gumming up. However, this will not work for an EGR valve that has already been gummed up.

Can my EGR be “blanked off”

Once again, in theory, yes it can and in some cases, it can improve the vehicle's performance and fuel consumption. However, it is altering the vehicle's emissions system, which is now frowned upon by the DVLA and if you are caught on the road with it being modified it can lead to fines, points and subsequently a ban. The engine’s ECU (electronic control unit) will also have to have its program modified (remapped) to prevent the engine management light from coming on, so by the time everything is taken into consideration, it’s not the best option.

The previous owner had the EGR blanked off, can that be reverted?

Usually, the reason it was blanked off was because the EGR valve itself has become problematic. Therefore, yes the blanking plate can be removed, however, it is likely that the EGR valve will need to be replaced (it will have to come off anyway to remove the plate) and it is highly likely that your engine control unit (ECU) will need to be programmed (remapped) back to standard.

Has my car got more than one EGR valve?

On some “V” configuration engines, there are indeed two EGR valves, a LH and a RH. We would need to know which one was faulty as there are often different labour times and parts depending on which side it is. You do not have to have both units replaced, however, do bear in mind that if one side has failed due to the deposits, the likelihood is that the other side isn’t far behind.

How many miles can you drive with a faulty EGR valve?

We would not recommend driving with a faulty EGR as it can lead to various engine performance issues and potential damage over time.

If the EGR valve is only slightly malfunctioning, you might be able to drive for several hundred miles, but you may experience reduced fuel economy, increased emissions, and minor engine performance problems.

If the EGR valve is severely malfunctioning and causing significant engine performance issues and knocking sounds you should avoid driving as much as possible. In this case, driving even a few miles can cause further damage to the engine and other components which can be a very expensive mistake.