Weak Vacuum Test

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