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Ive been noticing my check engine light comes ones when i hit a qauter of a tank. When i have the comp read. It says its my o2 sensor but i have replaced all of my sensors. Any ideas.

maybe you need to replace the cap{fuel tank}, or maybe you are not closing the cap hard enough. alot of times those fuel station guys they close the cap not to a hard tightness, and it gets loose later on. make sure you tell them or you close it you self hard enough. like 2-3 full turns.

why would your fuel cap make a cel come on ???

I dont see how that would make a difference. It only does it when i hit quater of a tank or lil lower. And i always makre sure my gas cap is on tight.

get some HEET. you may have gotten some watered down gas and when it gets to a quarter tank it delutes the gas to the point that the engine starts to stumble a bit, may not be enough for you to notice, but the engine sensors might.

could you provide us with the CEL number? then we could pinpoint the problem a bit better.

If i remeber right it said it was my downstream o2 sensor but ive replaced all of my o2 sensors not even 150 miles ago.

mmm....odd

were they quality replacements?
could you have water in your gas?
could it just be coincidence that it happens with 1/4 tank?

other than that im at a loss.

could be a possibility.

this is my .02, when you get down to that amt of gas, apparently your O2 goes berserk, it's not getting what it expects to be getting, meaning there's an issue with the mixture, since it only happens at a quarter tank, that mixture seems to have something ELSE being added/taken away (another chemical) It could be a bit of water in the fuel system, unlike oil and water, oil and gasoline can mix...i would get gas from somewhere else...it's probably old gas...u could also get some heet.

Idk y it does it. My girlfriends grandprix does it to. But i put some gas in it dis morning and the light went off like it normally does. I did go to a diff gas station to c if that makes it go away.  How much does heet usaully run.

no more than 5 bucks i believe.

yeah, heet is cheap, also heet has a couple of differnt choices.

http://www.goldeagle.com/heet/products.htm for more

i ussually go for the ISO-HEET, it works a bit better for removing water.

Ight kewl ill check into that tonight after work. thnz guyz.

Hey 97avengerguy... I seem to have the same problem.  My CEL comes on only if I let my tank get below 1/4 tank.  It's happened twice now.  I just bought the car so I have only refueled about 4 times.  When I clear the code it doesn't come back on unless I let the fuel brop below a quarter.  Maybe I too have water in my tank?

if you say all the O2s have been replaced:  what CEL code is it giving you? ya its a O2, but what? upstream, downstream, rear bank, front bank, rich, lean, lean front bank, lean rear bank, rich front bank, rich rear bank, etc...






CMC

I think it was the downstream but it was a faulty sensor. So my ligh doesnt come on anymore.

ok


CMC

Yep glad i still had a 30days warrnty on it casue iwasnt about to pay another 70buckes for it.

Yep, so much for that. My CEL came on today at 3/4 tank.   I read the code with a friend of mines ODB II code reader and it's says it's P0455. Evaporative emission control system leak (gross leak). Where would I look to fix this? 

If the avenger has a carbon canister, check it.  Failing that, get a new gas cap.