Fuel Rail Pressure (FRP) Sensor
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2018 Ford Transit-350 HD, 2018 Ford Transit-350, 2018 Ford Transit-250, 2018 Ford Transit-150, and 2018 Ford F-550 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
The fuel pressure sensor is a 3 wire variable capacitance sensor. The FRP sensor is located at the rear of the fuel rail (Transit) or at the front of the left hand side fuel rail (all others). The PCM supplies a 5 volt reference 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 fuel rail pressure 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.