Fuel Tank Pressure Sensor
WARNING: This page is about a different car, the 2003 Saturn LW200 and 2003 Saturn L200. However, it is still accessible from the selected car via links, so may be relevant.
Fuel Tank Pressure (FTP) sensor is similar to MAP sensor. It is used to measure the difference between the air pressure or vacuum in the fuel tank and outside air pressure. PCM supplies a 5-volt reference and ground to the sensor, and sensor sends a voltage signal back to the PCM.