DTC P0446: Evaporative Emission Vent System Performance ("A" & "B" Series): Description

A restricted or blocked Evaporative Emission (EVAP) vent path is detected by PCM monitoring the fuel tank pressure during normal operation. The PCM commands the EVAP vent solenoid off (open) and EVAP canister purge solenoid on (open). The fuel tank pressure should remain low as vacuum is drawn on EVAP system. If the vent path is blocked or restricted, vacuum level will increase and DTC will set.