EGR System - Diesel: Description

Exhaust gas recirculation (EGR) system is used to reduce oxides of nitrogen (NOx) by recycling some exhaust gas back into the intake manifold to lower combustion chamber temperatures.

The EGR valve is mounted on intake manifold. EGR system consists of an EGR valve, vacuum switching valve(s), and connecting hoses and tubes. An electronic EGR controller monitors throttle position sensor voltage and engine speed. Vehicles use a thermal vacuum valve to sense coolant temperature.