Exhaust Gas Recirculation: Notes
WARNING: This page is about a different car, the 2004 Ford Focus. However, it is still accessible from the selected car via links, so may be relevant.
The EGR system returns a small amount of exhaust gas into the intake manifold (9424). This reduces the overall combustion temperature. Cooler combustion temperatures provide a significant reduction of the oxides of nitrogen (NOx) in the exhaust emissions.