Fuel Temperature Sensor: Description and Operation

FUEL RAIL TEMPERATURE SENSOR

The fuel rail temperature (FRT) sensor is a thermistor. The FRT thermistor has high resistance when cold and low resistance when hot. The FICM supplies about 5 volts to the FRT sensor signal circuit. When the FRT sensor is cold its resistance is high and the signal voltage is high. As the FRT sensor warms and resistance drops, less signal voltage is monitored by the FICM. The FRT sensor voltage is sent to the PCM through a PWM circuit. The FRT signal is used by the PCM for fuel trim adjustment.