The VSV for EVAP is used to purge the evaporative emissions from the fuel tank into the intake manifold. Also, it creates a negative pressure (vacuum) inside the fuel tank in unison with the operation of the VSV for CCV (canister closed valve) and leak tests are performed using this vacuum.
Opening or closing malfunctions in the VSV for EVAP prompt the ECM to set DTC P0441.
The ECM checks for a VSV for EVAP "stuck closed" fault by commanding the VSV for EVAP open with the VSV for CCV (vent) closed. The fuel tank should develop a high negative pressure (vacuum). If it does not, the ECM determines that the despite an OPEN command, the VSV for EVAP remained closed. The ECM turns on the MIL and a DTC is set.
The ECM checks for a VSV for EVAP "stuck open" fault by commanding both valves (VSV for EVAP and VSV for CCV) closed at a time when the fuel tank is at atmospheric pressure. If the fuel tank develops a high negative pressure (vacuum) at this early stage of the test, the ECM determines that the VSV for EVAP is stuck OPEN. The ECM will turn on the MIL and DTC is set.