Large Leak Test

This tests for large leaks and blockages in the EVAP system. The control module will command the EVAP vent valve ON closed and command the EVAP purge valve ON open with the engine running, allowing engine vacuum in the EVAP system. The control module monitors the Fuel Tank Pressure (FTP) sensor to verify that the system is able to reach a predetermined level of vacuum within a set amount of time. The control module then commands the EVAP purge valve OFF closed, sealing the system and monitors the vacuum level for decay. If the control module does not detect that the predetermined vacuum level was achieved, or the vacuum decay is more than a calibrated level on 2 consecutive tests, DTC P0440 will set.