Circuit Description

PCM monitors amount of vacuum/pressure in EVAP system by monitoring fuel tank pressure sensor signal. PCM seals the EVAP system by commanding the EVAP purge solenoid off and EVAP vent valve on. PCM monitors fuel tank pressure sensor in order to determine if EVAP purge solenoid is leaking vacuum to EVAP system. This DTC sets if vacuum in EVAP system is greater than a predetermined value within a predetermined time. DTC will set when PCM detects a vacuum in the EVAP system when purge is not commanded.