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Exhaust Gas Recirculation (EGR), ch no 12020001-

Exhaust Gas Recirculation (EGR), ch no 12020001-


For a diesel engine operating with excess air in combustion, there is as yet no effective catalytic converter technology for reducing the NO x emissions. This means that the formation of NOx has to be restricted.

With an EGR-system (Exhaust Gas Recirculation), a controlled amount of exhaust emissions are directed to the induction side where they are mixed with the induction air. The result is slower combustion at a lower temperature and maximum pressure, which in turn inhibits the formation of NO x .

The EGR valve is electronically controlled and has its own processor. The EGR valve is controlled via a PWM signal at 140Hz from PSG 16.

Inside the EGR valve, the processor keeps track of how many valves are open. This means that when PSG 16 communicates how many should be open or closed, the response time is very short.

Having its own processor means that the EGR valve can perform self-diagnosis. If it catches or seizes for example, this is reported to the ECM with a PWM signal at 100Hz and a fault code is set. If a fault code is present for the EGR control, the engine will reduce torque and shut down the EGR and swirl functions. The Check Engine lamp will also come on.