Easy step by step instructions on how an automotive EGR valve works, this article
pertains to most exhaust gas re-circulation equipped engines.
Step 1 - An EGR (exhaust gas re-circulation) valve
is designed to lower NOX (NO2) gases that occur in the combustion chamber when temperatures
reach over 3,500 degrees Fahrenheit. NOX gases have been proven to cause brain damage
in humans, therefore EGR valves have been mandatory on most vehicles since 1976.
An EGR valve controls exhaust gases and allows them to enter the intake manifold
and flow into the combustion chamber at certain times in the operation of the vehicle
to reduce combustion chamber temperatures. There are different types of valves such
as electrically operated EGR (linear) and vacuum operated valves.