EGR valve: how it works

Able to fight nitrogen emissions (NOx), the EGR valve is environmentally friendly, but if dirty it can remain locked in the open position: in these cases what should you do? Let’s find out together.

EGR valve: how it works

The EGR valve is a component used above all in diesel engines : it intervenes to keep emissions within the ranges imposed by the new European regulations.

The main components of the EGR valve are:

  • the pipefor the exhaust gases
    • the EGR valve, controlled by the control unit
    • the pipe that connects the EGR valve to the intake manifold

The EGR valve reintroduces a small percentage of exhaust gas into the combustion chamber (up to about 15%) and lowers its temperature to reduce oxygen, reducing NOx formation.

Due to the impurities of the exhaust gases, the EGR valves can become dirty until they work badly: the worst situation occurs when they lock in the open position, and it is also the moment in which they must necessarily be replaced.

The EGR valve in petrol engines

The EGR valve is located between the intake and exhaust manifolds, and was created for diesel engines, as they produce more Nox, but is now also found on petrol-powered engines .

On the latter, reusing the flue gases serves to ensure faster temperature entry, with an accelerated heating phase that improves fuel consumption and emissions.

Either way, the new systems make the EGR valve outdated and superfluous , and for this reason too many people wonder what happens if it is eliminated.

Excluding (or removing) the EGR valve makes it necessary to change the operating parameters of the engine, which can take place thanks to the remapping of the electronic control unit: remember its elimination is illegal, and in any case you will have problems during the overhaul.

How to clean the EGR valve

The signaling of the dirty EGR valve starts from the signals of the on-board instrumentation with the warning light of a malfunction or failure of the engine, but could also be signaled by a sudden jerking trend (irregular minimum).

The cleaning of the EGR valve can be done manually disassembling the component (always by a mechanic), or by using additives for the fuel.

Remember that the greatest malfunctions of the EGR valve are recorded on small diesels, often mounted on cars that circulate for short journeys on urban roads: in these cases, the operating temperature is reached with difficulty and more damage is caused to the valve.

A note: for its replacement, the car manufacturers recommend a first check from 70,000 km, and the cost of an EGR valve is between 50 and 70 euros, plus labor.


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