Fuel Tank Pressure Sensor
WARNING: This page is about a different car, the 2003 GMC Sierra and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The Fuel Tank Pressure (FTP) sensor measures the difference between the pressure or vacuum in fuel tank and outside air pressure. The FTP sensor is located on top of fuel tank. The control module provides a 5-volt reference and a ground to FTP sensor. The FTP sensor provides a signal voltage back to the control module that can vary between 0.1-4.9 volts. As FTP increases, FTP sensor voltage decreases, high pressure equals low voltage. As FTP decreases, FTP voltage increases, low pressure or vacuum equals high voltage.