Theory Of Operation
WARNING: This page is about a different car, the 2015 Fiat 500. However, it is still accessible from the selected car via links, so may be relevant.
The Fuel Tank Pressure (FTP) Sensor provides the Powertrain Control Module (PCM) with information on vapor pressure inside the fuel tank. The FTP Sensor is a transducer that varies resistance according to changes in pressure. The PCM provides a 5 volt supply and sensor ground. The sensor sends a feedback voltage to the PCM on the signal circuit. As the fuel tank pressure increases, the feedback voltage decreases.