Patent ID: 7552716

Claim:
A common rail fuel injection system comprising: a common rail storing therein fuel under a given pressure which is to be injected into an engine; a fuel pressure sensor equipped with a sensor element which works to output a voltage signal as a function of a pressure of the fuel within said common rail; an electronic control unit equipped with a power supply circuit which is designed to supply a constant power supply voltage to said fuel pressure sensor through a harness, the constant power supply voltage being used in said fuel pressure sensor as a drive voltage applied to drive the sensor element, said electronic control unit working to feedback-control the pressure of the fuel within said common rail based on the voltage signal, as outputted from said fuel pressure sensor; a voltage sampling circuit working to sample the drive voltage applied to the sensor element of said fuel pressure sensor; and a voltage error monitor working to monitor whether the drive voltage, as sampled by said voltage sampling circuit is within a given voltage level or not, and when the drive voltage is out of the given voltage level, said voltage error monitor determines that the drive voltage is in error; wherein the harness connecting between said electronic control unit and said fuel pressure sensor includes a reference line through which said electronic control unit and said fuel pressure sensor are placed at a given reference potential, a first signal line through which the voltage signal is transmitted from said fuel pressure sensor to said electronic control unit, and a second signal line through which the drive voltage is transmitted from said fuel pressure sensor to said voltage sampling circuit installed in said electronic control unit.