Hi all, 04 Blazer, check engine light came on so I scanned it and it came out with P0455 evap emissions controls. I put on a new gas cap and it went off for about a week then the light came back on with the same code. I checked the evap canister lines and the purge solenoid lines and everything seems fine. What else could it be leaking?

 

can be anything under there if it just has a reallly small leak. one stupid thing you can check is the filler neck where the gas cap tighens down on. make sure it isnt a rusty mess. if it is just lightly sand it down and maybe put a bit of grease on the seal.

but really the proper way to diagnose these issues is with a smoke machine and you have to smoke the entire system. most common issues i see with gm's are the vent valves cracking or just not closing all the way

 

I crawled underneith and think I found it. The little canister above the spare tire that has the hose come from the evap canister was a bit loose. Pushed it back on and the light hasnt come on yet. Fingers crossed it stays off lol. Hopefully will fix my bad mpg, was getting 14-15 highway as opposed to the 20-21 I was getting.