This system is used to meter a small amount of exhaust gas back into the intake manifold to slow the combustion process, and slightly reduce the maximum temperatures in the combustion chambers, thereby reducing nitrogen oxides. A water temperature switch or three-way solenoid valve may stop exhaust gas recirculation when the engine is cold. On most models, the EGR Control Valve must be serviced periodically, and on some models, a maintenance warning system reset. The EGR valve is by far the most sensitive part of the system, as it can become carbon clogged.
NOTE: Fuel injected 323s do not utilize an EGR system.