The code reads "Evaporative emission control system leak detected (_____)" It tells you the size of the leak in the parenthesis; large, medium, small, very small. Those can be indicators of where to start looking. Very large or large could mean the cap wasnt on at all or there is an evap hose disconnected/broken. The other sizes point to things like the gas cap having a bad gasket or a cracked or split evap hose. Those hoses run from the top of your gas tank to your charcoal/fuel canister on your firewall.