Circuit Description
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
The DTC P0440 Evaporative Emission (EVAP) System diagnostic evaluates the operation of EVAP control system. Powertrain Control Module (PCM) will command EVAP vent valve ON, CLOSED, and purge solenoid and EVAP pressure switching solenoid ON, OPEN, with engine running. This allows engine vacuum into EVAP system. PCM then commands purge solenoid OFF, CLOSED, sealing the system. PCM then monitors fuel tank vapor pressure sensor signal to determine if there is vacuum decay. A rise or rapid increase in pressure indicates there is a large leak in the evaporative emission system. If PCM detects the vacuum level was not achieved and vacuum decay was evident a DTC P0440 will set.