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Home >> Buick >> 2008 >> Allure CXL >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Control System & Fuel System - 5.3L - DTC P0420 To DTC P3449) >> DTC P0451, P0452, P0453, or P0454 >> Circuit/System Description

Circuit/System Description

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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 also uses this FTP signal to determine atmospheric pressure for use in the engine-off small leak test, DTC P0442. Before using this signal as an atmospheric reference it must first be re-zeroed.