EGR System
WARNING: This page is about a different car, the 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, 2003 Chevrolet Monte Carlo, and 2003 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
The exhaust gas recirculation (EGR) system is used to reduce the amount of Nitrogen Oxide (NOx) emission levels caused by combustion temperatures exceeding 1500°F (816°C). It does this by introducing small amounts of exhaust gas back into the combustion chamber. The exhaust gas absorbs a portion of the thermal energy produced by the combustion process and thus decreases combustion temperature. The EGR system will only operate under specific temperature, barometric pressure and engine load conditions to prevent driveability concerns and to increase engine performance.