General Description (Exhaust Gas RECIRCULATION System): Operation
WARNING: This page is about a different car, the 2005 Dodge Stratus and 2005 Chrysler Sebring. However, it is still accessible from the selected car via links, so may be relevant.
When the engine coolant temperature is low, when the engine is at idle or when a wide open throttle operation is performed, the EGR valve is kept closed, achieving no EGR.
After warming up of the engine, the EGR valve can be opened by the engine control module (ECM) or powertrain control module (PCM).
The ECM or PCM monitors the EGR system and illuminates the Malfunction Indicator Lamp (SERVICE ENGINE SOON) to indicate that there is a malfunction.