Are you on the same tank of gas as when it first appeared? If the problem was moisture in the gas then it's still there. Run down the tank as much as possible before refilling.

I filled up again Sunday. I didn't even think of running the tank down. I have this disease....I fill up as soon as I dip below 1/2 tank.

Hmmm, is the moisture there from the previous tank or is it the gas station? I always go to the same Shell station.

> If the problem was moisture in the gas


Frankly, that explanation sounds like a bunch of BS to me. It would be interesting to see what the OBD-II code actually was. I hate to say it, but I get the feeling the mechanic probably just reset the code and sent it out with a "must of been moisture in the gas" rationale.

It will probably keep coming back and eventually the dealer will fix it.

!!! I would never let that happen... it always has to reach the 30mi range left or less before I even consider it... that damn warning bugs me and won't go away. ;) I have once let it go past 0mi, but only because I wanted to go to a specific station but there are stations at every other corner just in case. It didn't die even past 0mi for a couple miles more.

The code it threw was faulty ambient temp sensor DME F/C 2BCO. Replaced ambient temp sensor as per diag code D6581 00000000 01 001. The SA said the exhaust I was noticing and the hesitation/puter on the way to work that morning was probably due to moisture in the tank. I guess I should give better details next time.

Must be a guy thing. My ex used to take it to the limit all the time. It was like a challange to see how low he could go without running out of gas. IT MADE ME NUTS!

> The SA said the exhaust I was noticing and the hesitation/puter on the way to work that morning was probably due to moisture in the tank.


Frankly, I don't see how moisture in the tank would cause such a change in exhaust. More likely you are getting some moisture condensation in the exhaust system/muffler, which turns to steam as the vehicle warms up and makes the exhaust more noticeable. Depending upon which ambient air temperature sensor it was, it could potentially cause the hesitation and exhaust, as the engine computer uses ambient/intake air temperature as part of the engine management map.

If there is moisture in the fuel tank, you should remove it buy using a Red bottle of HEET deicer additive. This is isopropyl alcohol and will help burn the moisture out of the tank. Do not use the cheaper Yellow bottle of HEET, as that is methyl alcohol, which is not as effective and not as compatible as the isopropyl alcohol.

She might already have too much alcohol in her fuel. I think it could trip the same light as too much water in her fuel. The dealer can test a fuel sample and tell you if there is too much water/alcohol in the fuel. They might have to drain your tank. If so, you should have the service station pick up the bill.

Let us know what they come up with...

Craig

> I think it could trip the same light as too much water in her fuel.


How? Could you please describe the mechanism by which alcohol would result in an error code for an ambient air temperature sensor? Or another error code?

Too much alcohol in gasoline is quite rare, since Alcohol is more expensive than gasoline. It is mostly an urban myth.

P.S. Adding a bottle of HEET to the fuel tank will be about 1/2 percent isopropyl alcohol... insignificant in terms of engine operation.

I have a freind who is a local BMW mechanic. They've had two cars in the last few weeks with too much alcohol in the fuel. In MO, they can put up to 10% alcohol in our gasoline. He told me, the only way to tell is to take a fuel sample. It sounds like she has water in her fuel. Ask the dealer to take a fuel sample.

Let us know what they come up with...

Craig

> It sounds like she has water in her fuel

No, it doesn't.

Sorry, but I am a former mechanic and that does not sound like water in the fuel. And if it were, simply adding a bottle of red HEET while filling the tank with fresh gasoline would fix it in one tank of fuel, unless there was an enormous amount of water in the fuel.

Been there, done that.

I am not trying to be rude, but you are sending her on a wild goose chase which will waste her time, and, I might add, if it is water in the fuel, it will not be covered by warranty and will go into the permanent record of the vehicle, giving BMW an excuse in the future for eny engine problems. Far better to try a bottle or red HEET first.