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Che cosa è e a che cosa serve una valvola EGR

Model: (Various brands) Various
Part: EGR valve

Video tutorial

The EGR valve is an emissions control component found in diesel engines. Its purpose is to reduce nitrogen oxide (NOx) emissions, harmful gases that are produced during high-temperature combustion.

It is positioned between the exhaust manifold (from which the combustion gases exit) and the intake manifold (through which fresh air enters). Under certain operating conditions, the valve opens: instead of allowing all the exhaust gases to exit through the exhaust pipe, it directs a small portion (from 5 to 15%) back into the combustion chamber, mixing them with incoming fresh air. The exhaust gases are inert (they contain very little free oxygen) and hot, but less so than the explosion in the cylinder.

Reintroducing them has two fundamental effects: they dilute the air/fuel mixture by reducing the percentage of available oxygen and lower the maximum combustion temperature in the chamber. The result is that with less oxygen and lower temperatures, the chemical reaction that produces NOx is drastically limited.

Cleaning and replacing the EGR valve are common maintenance tasks after many kilometers.


Posted on 11 December 2025 by ScegliAuto


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