Vacuum Test At System Power-Up

NOTE: The diagnostic requires approximately 500 ms in order to run a completion. If the ignition switch is turned to the crank position too quickly, the diagnostic may not complete the test.

This test is conducted during a cold start (ECT = IAT +/- 8°C) with a fuel level that is between 85% and 15% and an engine that is not cranking.

Given the correct conditions at the system power-up, the PCM commands the vent valve open and purge valve closed. The fuel tank pressure sensor should indicate no pressure or vacuum during these conditions. If a pressure or vacuum is indicated, the [1][2]EVAP diagnostic is completed for that trip and a DTC P0446 is stored. If the conditions are not correct, this sub-test is skipped for this trip.