OBD II Serviceability Issues: Refueling
WARNING: This page is about a different car, the 2006 Suzuki Reno and 2006 Suzuki Forenza. However, it is still accessible from the selected car via links, so may be relevant.
A new OBD II diagnostic checks the integrity of the entire Evaporative (EVAP) emission system. If the vehicle is restarted after refueling and the fuel cap is not secured correctly, the on-board diagnostic system will sense this as a system fault, turn ON the MIL and set DTC P0440.