Exhaust Gas Recirculation (EGR) Valve

The exhaust gas recirculation (EGR) system is used to lower oxides of nitrogen (NOx) emission levels caused by high combustion temperatures. The main element of the system is the EGR valve which is operated electrically by the engine control module (ECM).

The EGR valve feeds small amounts of exhaust gas into the intake manifold to decrease the combustion temperature. The amount of exhaust gas recirculated is controlled by variations in electrical signal and exhaust back pressure. If too much exhaust gas enters, combustion will not take place. For this reason, very little exhaust gas is allowed to pass through the valve, especially at idle.

The EGR valve is controlled precisely by the ECM according to various operating conditions of the engine.