EGR valves increase engine efficiency whilst at the same time decrease emissions.

When the EGR valve is clogged or malfunctioning, engine performance can deteriorate and the EGR valve should be inspected, cleaned or replaced.

The EGR valve works by recirculating some of the car's exhaust gases back into the engine combustion chamber.

By doing this, the temperature in the engine is lowered.

Nitrogen oxides produced by the engine pollute the atmosphere less if they are cooler.

Your EGR valve therefore has a direct impact on vehicle emissions and should ideally be checked prior to an MOT test.

An EGR valve consists of a small valve which opens to allow exhaust into the combustion chamber and closes when it is not needed, to keep the air mixture optimal for combustion.

Some versions do not open until there is sufficient back pressure, ensuring that the valve will not be open when the engine is idle or cold, providing a higher concentration of oxygen for combustion.

If your EGR valve is stuck open, it will lead to inefficient combustion, rough idling, hesitation, and sometimes engine stalling.

The EGR valve is simple and quick to clean or replace.

If it is clogged, simple cleaning will solve the problem.

Replacement of the valve may be needed if there are mechanical issues.

Failure to repair or replace the valve will not lead to any dangerous driving conditions, however it will reduce the engine life of your car and increase the potential emissions which will be apparent on your next MOT test.