Fuel Rail Pressure (FRP) Sensor
The fuel pressure sensor is a 3 wire variable capacitance sensor located at the front of the left hand side fuel rail. The PCM supplies a 5 volt reference (VREF) signal which the FRP sensor uses to produce a linear analog voltage that indicates high fuel pressure. The primary function of the FRP sensor is to provide a feedback signal to the PCM indicating the pressure of the fuel in the fuel rail. The PCM monitors FRP as the engine is operating to control fuel pressure. This is a closed loop function which means the PCM continuously monitors and adjusts for ideal fuel rail pressure determined by conditions such as engine load, speed and temperature. The fuel rail pressure can be monitored by viewing the scan tool FRP (volts) and FRP_A (pressure) PIDs.