Weak Vacuum Test

This tests for large leaks and blockages in the EVAP system. The PCM will command the EVAP vent valve ON (close), and the EVAP purge valve ON (open) with the engine running, allowing engine vacuum into the EVAP system. The PCM monitors the fuel tank pressure (FTP) sensor to verify that the system is able to reach and hold a predetermined level of vacuum within a set amount of time. If the PCM does not detect the predetermined vacuum level on two consecutive tests, DTC P0440 will set.