Functions of an EGR Valve

EGR valve

Mechanic (Pneumatic) EGR valve

EGR (Exhaust Gas Recirculation) valves recirculate a portion of the exhaust gas from the engine (5% to 15%) back into the combustion process. This ensures that the fuel gets completely burned while decreasing the production of harmful gases such as nitrous oxide. Simply put, it is a valve that opens and closes as needed.

Some vehicles have an electric EGR valve while others are mechanical (pneumatic). These are explained further below.

Benefits of a Fully Functioning EGR Valve

1. Less Emissions.

The recirculated gas keeps the engine cool inhibiting the production of harmful gases such as nitrous oxide that can only form in temperatures of above 2500 Fahrenheit.

2. Reduction of throttle loss on spark ignition engines.

3. Extends the life of the engine chamber by reducing its exposure to high temperatures.

How to Know When an EGR Valve needs to be replaced

EGR valves can become damaged or malfunction from a build-up of carbon and other materials from the exhaust gases. This can cause them to become wedged open, closed or completely malfunction.

In modern cars the ECU (Engine Control Unit) can detect issues with the EGR valve and display a warning on the dashboard to alert the driver. The most common fault codes associated with a faulty EGR valve are listed below:

P0401 – Insufficient EGR Flow
P0402 – EGR Excessive Detected
P0403 – EGR Circuit Malfunction
P0404 – EGR System Performance
P0405 – EGR Pintle Position Circuit Low Voltage
P1404 – EGR Valve Stuck in Open Position
P1406 – EGR Valve Pintle Position

Other Symptoms of a Malfunctioning EGR valve are:

1. Increase in Exhaust Particles (Partially Burned Fuel)

Dirty EGR Valve

EGR Valve blocked with Exhaust Particles

An EGR valve that is faulty and remains open will increase the amount of exhaust particles leading to the diesel particulate filters (DPF’s) becoming blocked quicker.

2. Detonation (also known as knocking, spark knock, pinging or pinking)

This occurs when there are small explosions within the engine’s combustion chambers. This can cause mechanical damage, abrasion and overheating.

3. Rough Idle & Misfiring

When the EGR valve fails to close it causes exhaust gas to leak into the intake manifold.

4. Hard Starting

An EGR valve that fails to close can result in a vacuum leak into the intake manifold.

Should I remove or Block an EGR Valve?

  • Blocking or removing EGR valves is not recommended. There is a common misconception that doing so will provide more power, however this isn’t true. Furthermore, as one of its functions is to recirculate exhaust gas to ensure the fuel is completely burned it is saving you money by making your engine more efficient.
  • It can also result in a NCT (National Car Test) or MOT (Ministry of Transport) test failure due to emissions.

How to Buy EGR Valves on

EGR Valve Example (Electric)

EGR Valve Example (Electric)

While we try to narrow down the search results for EGR Valves by using the registration number search or car drop down search, these systems may not be able to provide enough information to narrow the search down to one type of EGR valve.

The most important thing to know is if the EGR valve is electric or mechanical (pneumatic). This information will be clearly stated in the description of the product under Operating Mode. An example of this is shown on the right hand side.

See the images below and compare them with the one fitted on your vehicle.

Electric EGR Valve
Electric EGR Valve
Manual (Pneumatic) EGR Valve
Manual (Pneumatic) EGR Valve












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If you’re interested in learning more about car parts see our other articles here.