DTC P0455-00: Evaporative Emission System-Leak Detected (Large leak): General Description

The ECM monitors the Fuel Tank Pressure (FTP) sensor in order to determine the level of vacuum/pressure in the Evaporative Emission (EVAP) system. The ECM commands both the Purge Control Solenoid Valve (PCSV) and the Canister Close Valve (CCV) "ON" when the conditions are met in order to apply an engine vacuum to the EVAP system. The ECM commands the PCSV "OFF" once the system has reached a predetermined level of vacuum. This test verifies if a vacuum can be achieved in the EVAP system. Failure to develop a vacuum may be caused by a large leak or a restriction.