Purge Solenoid Leak Test
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
If the EVAP purge solenoid does not seal properly, fuel vapors could enter the engine at an undesired time, causing driveability concerns. The control module tests for this by commanding the EVAP purge solenoid OFF, closed; and vent solenoid ON, closed; sealing the system, and monitoring the FTP for an increase in vacuum. If the control module detects that EVAP system vacuum increases above a calibrated value, DTC P0496 will set.