Details:
There is a leak in your fuel vapour system. This might be a hose, connection or your gas cap may simply be loose (most leaks are due to the latter). Some gas caps do wear out over time. Replace gas cap (less than $8 at any automotive store) first or you'll need the dealer or trained auto technician to find any other leaks which could be in hoses to/from carbon canister, charcoal canister itself, the EVAP control module or in vacuum lines around it, fuel tank and filler neck and purge control (EVAP) valve located on or close to engine top and/or throttle body.
