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Where are you located? I'm thinking you are getting condensation in your tank. While these are supposed to be sealed fuel systems, I'm sure, if there's empty space in the tank that atmospheric air is gonna get in there.

Do you run with less than half a tank most of the time? I know some folks, my kids for example, rarely have much more than a quarter tank.

If you live in a humid climate where the temperature drops below the dew point in the evening, then you could be getting condensation in the tank. The more empty space in the tank (well, it's not really empty - it's full of air) the more condensate you will get.

I'm not positive of this diagnosis, but the mention of Heet fixing it for a while makes me think it's moisture (H2O). As I recall, products like Heet loosely bond with both the water molecules and the gasoline molecules, which has the effect of dispersing the water throughout the fuel rather than having it concentrated in one blob at the bottom of the tank where the fuel pickup resides. This effectively dilutes the water with gasoline rendering it insignificant.

Or, it could be crappy gas. In that case, the condensation occurs in the underground tank at the gas station. Where do you buy your gas? Do you use the same place(s) consistently? Is it a brand name fuel(s)?

There are a few places around here I avoid. Usually, it's because I notice my car or truck running like crap after I fill up there, until I fill it up again somewhere else.

Besides the code, do you notice any other symptoms such as rough idle or hesitation?


Doug

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I let my tank get down from time to time, but fill it up to completely full at least twice a week. I live in Ohio where it gets below freezing one day and then hits 60 the next. It is happening a lot like that right now. I fill up at only Costco and Speedway locations. I refuse to buy my gas anywhere else.

Parking in a heated garage ?

No sir.

Common problem due to a defective fuel sensor - or a correct problem if you are buying gas that has water in it. Since the error code - have you continue to buy gas at the same station?

I only buy gas at Costco and Speedway locations.

Is this a flex-fuel vehicle?

Yes.

So an update, I called GM Customer care and they said that this has been reported to them numerous times lately with these cars. They have issued me a $100 diagnostic coupon to have the car looked at for free. Anything that they find should be covered under a warranty they said. The customer service rep on the phone made it sound like they would recall this part soon as the flex fuel sensor seems to be defective.

 

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So, I thought that I should give an update. I took it to the dealership a couple weeks ago to have it diagnosed. They found that the fuel composition sensor on this was bad from the factory and were very surprised that it hadn't given me problems earlier. They replaced it (and a lot of other things) under my extended warranty. I think that this may be getting recalled soon. Also, Marathon Petroleum just announced that they have received the Top Tier certification.

 

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I don't use any Exxon gasoline.