Hi guys, H3-2006-ADV-115k

I'm having a check engine light, the scanner throws the gas cap code and a bad valve somewhere in the fuel system. I've replaced the cap twice and when I have a full tank the light disappears, however, if it goes below half it appears again.

My thoughts are that there's a problem in the canister or the valve (don't know the name) but I don't really know much about how this system works.

Any suggestion on how to fix this?

 

Evap canister, in the rear above the rear differential.
There are YouTube videos on purging and cleaning the system.
If that doesn't work you may need to buy a new one.

 

Here is the part https://www.amazon.com/gp/product/B0...iglink22697-20

 

And a thread here ... https://www.hummerforums.com/forum/h...control-30289/

 

I'll try that. Thanks!