Electronic Control Unit (ECU):

The electronic control system consists typically of the following components:

Electronic control unit (ECU), Fuel lift pump, Crankshaft speed/position sensor, Camshaft position sensor, Accelerator pedal position sensor, Turbocharger boost pressure sensor, Air temperature sensor, Coolant temperature sensor, Air mass meter, Fuel pressure sensor, Fuel injectors, Fuel pressure control valve, Preheating control circuit, EGR valve actuator.

The information from the various sensors is passed to the ECU, which evaluates the signals. The ECU contains electronic  maps which enable it to calculate the optimum quantity of fuel to inject, the appropriate start of injection, and even pre- and post injection fuel quantities, for each individual engine cylinder under any given condition of engine operation.

Additionally, the ECU carries out monitoring and self diagnostic functions. Any faults in the system are stored in the ECU memory, which enables quick and accurate fault diagnosis using appropriate diagnostic equipment (such as a suitable fault code reader).