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 located at the top left of the engine in the fuel injection pump supply tube, forward of the secondary fuel filter. The FRT sensor measures the temperature of the fuel at the secondary fuel filter 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.