Exhaust Gas RECIRCULATION: Description

The purpose of the exhaust gas recirculation (EGR) system is to limit the formation of oxides of nitrogen (NOx) emissions. This is done by reducing the high peak combustion temperatures at which NOx is formed. By reintroducing some exhaust gas back into the combustion chamber, the high temperatures are avoided and thus NOx emission formation is reduced.

System consists of a vacuum-operated EGR valve and a coolant temperature override (CTO) switch. In addition, some models are equipped with an air cleaner-mounted thermal vacuum switch (TVS), and some models are equipped with an EGR vacuum dump valve.