Diagnostic Aids
Check for foreign object or debris holding purge solenoid valve open. If purging is occurring, voltage reading will rise when EVAP system seal is commanded on.
An intermittent condition may be caused by poor connection, rubbed-through insulation, or a broken wire inside insulation. Check PCM harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, or poor terminal-to-wire connections before component replacement.