Exhaust Gas Recirculation (EGR) System (BMW 5 Series E39)

The fuel system of diesel engines is equipped with an exhaust gas recirculation (EGR) system, which reduces the amount of harmful nitrogen oxides emitted into the atmosphere (NO_x). To do this, part of the exhaust gases are fed back into the engine combustion chambers, which lowers the combustion temperature and thereby reduces the content of harmful substances in the exhaust gases. The recirculation process is controlled by the DDE control unit, which, based on signals from the accelerator pedal position sensor, crankshaft speed, atmospheric pressure, and coolant temperature, issues commands to change the cyclic fuel supply. In accordance with this, the control unit, using a vacuum control valve, supplies vacuum pulses to the EGR valve and ensures the correct dosing of the amount of recirculated exhaust gases. The EGR valve is located at the intake manifold. At low coolant temperatures and when high engine power is required, exhaust gas recirculation is not performed. The EGR system does not require maintenance.

(Information obtained from this online resource: «www.bmwman.ru»)