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Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 231 (Engine Controls - 3.9L - DTC P0442 To P2A01) >> DTC P0446 >> Circuit/System Description

Circuit/System Description

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This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid valve Open and the EVAP canister vent solenoid valve Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Open. The control module monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inch H2O in a calibrated time, this DTC sets.

DTC P0446

FTP Sensor Signal Voltage Fuel Tank Pressure
Low, Approximately 1.5 V or less Positive Pressure
High, Approximately 1.5 V or more Negative Pressure/Vacuum
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