DTC P0455: EVAP Control System - Gross Leak Detected: Description
WARNING: This page is about a different car, the 2002 Nissan Pathfinder and 2002 Infiniti QX4. However, it is still accessible from the selected car via links, so may be relevant.
This diagnosis detects very large leaks in the EVAP system (fuel filler cap fell off) between the fuel tank and EVAP canister purge volume control solenoid valve.