DTC P0446: Evaporative Emission (EVAP) Vent System Performance: Description
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A restricted or blocked Evaporative Emission (EVAP) vent path is detected by Powertrain Control Module (PCM) commanding purge valve on (open) and vent valve on (closed) allowing a vacuum to be applied to EVAP system. Once a calibrated vacuum level has been reached, PCM commands purge valve off (closed) and vent valve off (open) while monitoring Fuel Tank Pressure (FTP) sensor for a decrease in vacuum.