Circuit Description

A vacuum switch in the purge line is used to detect when system is being purged. The normally-closed switch will open when 5 in. H2O or greater is present in purge line. Powertrain Control Module (PCM) supplies a 5-volt reference to the switch to monitor if EVAP system is functioning properly. If switch is off (no purge detected) when PCM commands purge, DTC P0441 will set.