Fuel Rail Temperature (FRT) Sensor
The FRT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical voltage signals to the PCM corresponding to temperature.
The sensor is mounted on the high pressure fuel injection pump. The FRT sensor measures the temperature of the fuel at the inlet of the high pressure fuel injection pump and provides a feedback signal to the PCM. The PCM uses the FRT sensor input to command the correct fuel injector timing, the pulse width, and the correct injection control pressure for correct fuel delivery at all speed and load conditions.