Fuel Rail Temperature Sensor
WARNING: This page is about a different car, the 2004 Ford Pickup Heritage. However, it is still accessible from the selected car via links, so may be relevant.
The fuel rail temperature (FRT) sensor is used to calculate fuel density (the amount of vapor within the fuel rail). The FRT sensor is a thermistor style element that converts temperature into voltage. The resistance of a thermistor decreases as the temperature increases and increases as the temperature decreases.