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Exhaust Gas Recirculation (EGR) System Description: Notes

Fig 1: Identifying Exhaust Gas Recirculation (EGR) System
GM1913727Courtesy of GENERAL MOTORS CORP.

The exhaust gas recirculation (EGR) system is used to reduce the amount of nitrogen oxide (NOx) emission levels caused by combustion temperatures exceeding 816° (1,500°F). 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 decreases the combustion temperature. The EGR system will only operate under specific temperature, barometric pressure (BARO) and engine load conditions in order to prevent drivability concerns and to increase engine performance.