Check Engine Light & faulty gas caps
 

Recently my 06 H3 with 58k miles had a check engine light coming on, the code P0455 (EVAP leak), the dealer detected smoke coming out the cap when tested. Now two weeks later with a new gas cap the light comes on again and the code again detects same large leak in the EVAP system with the same probable causes (1. fuel cap 2. EVAP canister 3. purge or vent solenoid defect 4. vac leak at engine) & yes I have been properly filling the tank and screwing the cap on right. I had the dealer clear alarm off to test again, the question is how long does it take for the computer OBO to diagnose this emission issue. I've been driving about a week and so far it hasn't come back on. I'm thinking it's just a matter of time. Is there a set detection cycle the OBO follows weeks or days?

I have a 2006 Hummer H3, and when I use Shell gasoline, as opposed to the the Phillips and Conoco, the check engine light always comes on. For some weird reason just when I use shell gasoline. What I do to make the light go away is to take the fuel cap off while it is running and then adjust it back on. After about 20 min off driving it turns off and never comes back. The manual taught me this. I'm thinking you use a very high octance of gas or something, or maybe too low octane. Mine light always comes on when I use Shell and I have to use the full tank sometimes to make it go away, hope this helps you out.

Thanks Chrome but I've been using the same octane from Costco for years without any problem until now so I can rule that out.
anyway this weekend the FUEL CAP digital warning flashed then stopped followed by the CEL came back on as expected after only less than 15 cycles of hot and cold engine so that was quicker than what has been posted on this forum.
Not sure how a fuel cap which was changed to a new one on the previous dealer visit and say now a EVAP solenoid can go out at the same time. Something fishy is going on here.

Followup: back at dealer smoke test this time found VENT VALVE leak (valve sticking open) this locate back near canister, replacement part $178 & labor extra. So just under $500 gets me a new gas cap and vent valve. hummm

Well humdog that doesnt mean that costco hasnt had problems with their fuel
 

Well humdog that doesn't mean that costco hasn't had changes to their fuel by changing their wholesaler or their formula or water in their tankes or have had some other sort of fuel change or adding cleaners to their fuel or any number of other possible changes..... abesides our 2003 H2 Hummer we own a highly customized 2002. Dodge Ram Quad 4x4 ad have had this same problem with it too, and the two vehicles are as different as you can get but they seem to have he same problen with This error and ive done the fuel cap swap and checked the hoses and solenoid and valve and everything else to try and get rid of the problem.... with my H2 it seems to happen if the tank hasn't had a full fill in a while and ive cleared the code and it didn't come back for a long long time until a couple days ago my wife came home from the store and told me the engine light came on so I reset with my scanner and filler the tank and ill wait to see if it comedy back on again? What a lot of people don't realize is that running your vehicle with less then a half or quarter full tank it can cause problematic in the fuel and emissions systems because not only does the pressure in the tank fluctuate a lot but every tank has moisture in them no matter what you do its going to get in there and running your fuel tank really low on gas means more of this moisture is allowedly to get into the fuel system.... and there are all sorta of little metal fittings and parts that are prone to rust so by keeping your tanker more full then not you'll keep some problems to a minimum...
... anyway the point I was trying to make is that just because you haven't changer gas stationary or the octain rating doesn't mean your gas station hasn't made some changes to their fuel or fuel mixture, it could also be that their octain rating isn't actually what it is advertiser as being..... anyway good luck and just remember that it isn't just a hummer problem because pretty much all vehicles with these systems in them have the same problems and it doesn't matter if you drive a Hugo or a ferrari its still going to happen

Sandman

What the "Check Engine" light really means?
 

It's really a coded message to the dealer that means "Got a Sucker" or "Merry Christmas, here's your $600 present" depending on the time of year.

My '06 H3 check engine light came on new years eve, went to the dealer, he did a quick diagnostic check and promply showed me a laminated color picture of my emmision system as he pointed to the fuel canister located under the gas tank. "Your fuel vent is bad, but you're in luck, we have one in stock and can do it right now. We will have to remove your gas tank to do it and it will cost you $600."

Amazing. I can't help but wonder how many times they pull this crap off to unsuspecting customers. Seems Mr. Goodwrench has watched the Wizard of Oz once too many times and now has become the guy behind the curtain pretending to fix your car.

And they wonder why we drink?

Good Luck Goombas, it's a jungle out there ... speak softly and carry a big gun!

-Papa Joe

yeah!like check out that engine light!
 

i read this for fun and the post above it. its really fun to look at what people "make up: in their heads and then believe it.
do you wonder why more of the moisture would get into the system with the gas low if the moisture is in there anyway?
do you wonder just how many parts that are prone to rust are designed into the fuel system? like a cast iron pickup tube!!

now the stuff about dealer revenue enhancement, i can see that

edit. after posting , i went out to get mail,removed my gas cap and drove out the driveway,took the long way back,drove in circles in the snow to count my tire tracks,started on off 6 times,drove another trip thru the field. how do you get a gas cap light??
i put the cap back and came in

What tue Hell are you babbling about?
 

Uhmm dude what exactly are you trying to say? What are you babbling about? Do you just type to see yourself talk?? What's your point because nothing you said pertains to anything in the post and makes absolutely no sense whatsoever and if your going to post a message try to do so within the scope of the conversation... There's already enough problems with smart ass posters so we can do without another one on here so please for the love of god make sense and tell us what your trying to say!!! Or make a valid point or argument to agree with or disagree with the topic or provide information that can help fix the problem but don't just pop in and post a message that makes no sense or doesn't help the people figure out the problem.... Were here to try and help each other out and try to provide information that can help remedy the problems were all having..... I mean the whole point is to help fix problems not to just come on here and be a smart ass so if you've nothing to provide to help then just go elsewhere please

Before you go throwing the good Dr. under the bus, be aware it was yourself that replied to a thread that was over a year old. ;)

haa!
 

i missed the old date!!
i am curious however why i dont get a code when i let my cap hanging there! and that DOES relate

oh, just for fun, this is babbling!!!!

Quote:
but every tank has moisture in them no matter what you do its going to get in there and running your fuel tank really low on gas means more of this moisture is allowedly to get into the fuel system.... and there are all sorta of little metal fittings and parts that are prone to rust so by keeping your tanker more full then not you'll keep some problems to a minimum.

just not so,,,just babbling