Purge Valve Leak TestEVAP System Components

If the evaporative emission (EVAP) purge valve does not seal properly, fuel vapors could enter the engine at an undesired time causing driveability concerns. The control module tests for this by commanding the EVAP purge valve OFF closed and vent valve OFF OPEN, and monitors the fuel tank pressure (FTP) for an increase in vacuum. If the control module detects that EVAP system vacuum increases above a calibrated value, a DTC sets.