The function of the EGR system is to reduce Oxides of Nitrogen (NOx) in the exhaust gas, which are the result of high combustion chamber temperatures. The combustion chamber temperature is reduced by directing a portion of the spent exhaust gases into the combustion chamber along with the incoming air/fuel mixture. The lower temperature in the combustion chamber results in reduced amounts of NOx.
The EGR system consists of the EGR valve and various sensors and solenoids which regulate the induction of exhaust gas.