The evaporative emission (EVAP) system contains the following
components:
| • | The EVAP fuel vapor canister |
| • | The EVAP purge solenoid valve |
| • | The EVAP fuel tank pressure sensor |
| • | The fuel vapor and vent lines |
The powertrain control module (PCM) will command the EVAP purge solenoid
valve ON to purge stored fuel vapors from the EVAP fuel vapor canister. The
PCM will pulse width modulate the on-time of the solenoid in order to regulate
the amount of fuel vapor entering the engine. The PCM will enable purge
during most driving conditions, including idle based upon sensor inputs.
The PCM runs a comprehensive diagnostic test of the EVAP system. A failure
of the EVAP system will set a DTC. The EVAP vent valve and the EVAP fuel
tank pressure sensor are needed by the PCM to diagnose the EVAP system.
