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Pure gas -> check engine light?

Hello. Yesterday I filled up my 2003 VW Passat with straight gasoline, no ethanol, for the first time. After I started driving, the check engine light came on. I have since finished that tank (been traveling) and filled it up with the usual 10 percent ethanol. Will the check engine light go out on it’s own if related?

Where did you get “straight” gasoline with no ethanol? As far as I know, all gas sold in the US has “up to” 10% ethanol added as an oxygenator to reduce emissions. I live in the Boston area, and I remember a few years ago I did some research on the “actual” ethanol content of gasoline sold in this area. As I recall, the % ethanol varied from winter to summer because seasonal temperature variations changed the amount of ethanol required to achieve the desired emissions chemistry, but I think I remember it varied in the 6-8% range. It never got/gets to the “up to 10%” level quoted on the stickers on the pumps, at least not in this region.

But, back to the original question, where do you get gas with ZERO ethanol?

Well, I guess I haven’t gotten out of Boston enough…I just found a map showing gas formulations around the country, and i see that “pure” gas is available most places in the heartland…

But to answer your question, your check engine light could mean just about anything. You can have it diagnosed for free by taking it to an auto parts chain store like Auto Zone and asking them to put a code reader on it. Be sure to take a pen and write down the actual code digits. If you report back here with the actual code, the regulars on this forum who know more than I do will be happy to tell you what that particular code might mean.

Odds are the CEL has nothing to do with the type of gas. Get the car scanned for any codes and see what pops up.

Around here, one has to go out of their way to get Ethanol because no one wants it; including the farmers who grow the corn used in the production of it.

Pure coincidence. The lit CEL is informing you of some unrelated problem. Switching fuel did not turn it on, and going back will not turn it off.

jesmed, you can find fairly good listings of places that sell ethanol-free gas on the puregas website (pure-gas.org). There is considerable variability by state, but it is available throughout the country.