Exhaust Gas Recirculation: Description and Operation

EGR Circuit:

The EGR system operates to reduce oxides of nitrogen (NOx) emissions. When the engine is under load, the EGR valve admits a small amount of exhaust gas into the air/fuel charge, effectively reducing peak combustion temperatures. Greater amounts of exhaust gas are metered in as engine speed and load are increased. The ECM calculates various input information to control EGR valve operation.