EVAP Emission Control Sys., plz help
 

I received the light on my dashboard "service engine soon", I hooked up my OBD II and got code P0455 EVAP Emission Control System Leak (Large). Before I'll go to a local "stealer" I would like to find out if I can do anything my self in the order to take care of this defect? I clear the light with OBD II but I know that the light will probably come back. I run the test with OBD II this morning again and doesn’t show any faults, but I'm not sure if there is still something wrong.
I don't know if this has something to do with the fact that I poured in about a month ego Lucas Injector Lubricant and Cleaner into my gas tank...?
I looked on DIY section and I don't see any helpful information on this repair, unless I overlooked. Can any body help, please. Thank you.Regards

This is almost always leaving the gas cap off, loose, or otherwise leaking with the engine running.

thx. u are right, I forgat about this option...I'll wait before I do anything and make sure in meantime that my fuel cap is tight. I ren the test again and it doesn't show any foults...let's hope this is it...thank you.