Fuel Pressure Sensor
The Fuel Pressure Sensor detects the fuel pressure (actual pressure) of the fuel pump.
The fuel pressure measured by a measuring capacitor coupled with the Fuel Pressure Sensor.
When fuel pressure increase, the gap between the capacitor electrodes decreases. The capacitance, and therefore the signal voltage, thus increase in proportion to the fuel pressure.
The signal voltage serves the FPCM as information about the fuel pressure.