General EGR System Operation:

WARNING: This page is about a different variant/trim than selected.

The Exhaust Gas Recirculation (EGR) system consists of a high pressure and low pressure EGR system. The two systems are controlled independent of each other, but are operated in a manner to work together for total EGR flow. Both systems consist of an EGR valve to control flow. A cooler assembly is used to reduce the temperature of the exhaust gas that is recirculated to the engine, which in turn helps reduce NOx emissions. An EGR temperature sensor is used to monitor temperature and flow through each system. The EGR valves can be commanded to open at a variable rate between open and closed. This allows the Powertrain Control Module (PCM) to operate either system at 100% of the total flow or blend the rate of flow between the two systems.

Low pressure EGR is introduced above 55°C (131°F) coolant temperature and increases in percentage of total flow as the engine temperature increases. High pressure EGR flow decreases in percentage of total flow as low pressure EGR flow increases.

On a normally operating system, the total EGR flow consists of the following:

flow 100% from the high pressure EGR system when the engine is cold - under 55°C (131°F)
blend the two systems increasing low pressure EGR and decreasing high pressure EGR during engine warm up above 55°C (131°F)
flow 100% from low pressure EGR when the engine is hot