System Description
WARNING: This page is about a different car, the 2006 GMC Yukon XL, 2006 Chevrolet Suburban, and 2006 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the Evaporative Emission (EVAP) System. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies, depending on EVAP System pressure or vacuum. The controller uses this FTP signal to determine atmospheric pressure for use in the engine-off small leak test, P0442. Before using this signal as an atmospheric reference, it must first be re-zeroed. If the FTP signal is out of range during the re-zero procedure, this DTC will set.