This study analyzed by measuring the voltage waveform of the injector intended for operating CRDI diesel vehicle. The cases of the EGR trouble and a EGR normal is considered. 1) The voltage waveform in the case of the normal and trouble, the difference between the maximum voltage was not large, decrease in the number of voltage gated pulses with the increase in engine speed, sustained current remained for this period. 2) The voltage waveform, comparing the case of the normal case and trouble, the size of the maximum voltage, no large change in gate pulse voltage is to be generated than in the case of a defective irregular longer opening time of the injector factor it was possible to know the bad influence on the fuel efficiency.