So recently I hopped in my H3 to drive home and when I turned it on the check engine light popped on, It ran completely normal and when I got home I decided I'd got to auto zone to get a error code. Anyways fast forward a couple hours and the error code is P0440, now I checked to see my gas cap was tight and it seems like it is but i ever since I got the car I never trusted the cap because to me it seemed a bit flimsy. But before I go spend $30+ on a new cap I decided I'd come here and see if you all think thats the problem and if you think I need a new cap. Keep in mind it's been a couple days since I made sure the cap was tight and the check engine light has not turned off. I'll post pics of the cap and bezel as well so you guys can see for yourselves

cap and bezel

cap unscrewed

cap

 

Welcome to HF from another Mitten dweller.

Wipe the dirt and crud off the Gas Cap Gasket and the filler mouth edge that the Gasket seats against.

When you put the Gas Cap on keep tightening until it clicks. Drive it for a while and see if it comes back.

Try that first even though it is highly likely that is not your problem. Gas Cap issues cause the "FUEL CAP" message to be displayed in the DIC. You probably have an EVAP leak or Purge Valve issue.

 

X2. By the looks of your pics, moisture is getting passed the seal(rust spots). Thoroughly clean wipe out the filler and clean the seal on the cap and silicone spray the seal too.

 

Thanks for the help guys, I'll be sure to try out your guys' suggestions as soon as I can, now I'm sure my hummer doesn't have a check gas cap light because I've let my dad drive my Hummer before and it's literally happened twice in the past where he fuels it and when he gets home with my baby I see it's gas cap unscrewed and I die a little bit inside yet when he was driving there was no check engine light or check gas cap light on.

 

FYI, P0440 minor leak detected. P0456 major leak detected, that throws when fuel cap is left off.

 

I had the same issue, finally found a pin hole in the fuel pump assy plate, after replacing the fuel cap. Yeppers michigan salt.

 

I just want to say that the issue strangely solved itself. one day about a month ago I turned on the H3 and the check engine light was nowhere to be found. Guess the cap must've been loose at some point. Thanks for all the tips guys.

 

You have a self cleaning gas cap?

 

To be fair I cleaned it a bit and put some vaseline type stuff on it but im not sure how much it did, either way no issues anymore. Yeah beats me too man.

 

[QUOTE=hummerz;365630]You have a self cleaning gas cap? [/ I asked your help but I did not expect this attitude.Who am I?A new member who needed your help and not your big mouth.Thanks for your funny video too.Where are you located at?