I have a wicket bad 02 sensor proplem. I've been driving my car for about three months now with no proplems, but about 2 1/2 weeks ago I ran a little bit of racing fuel (which was leaded). last week I started to get a 02 code so I pulled the 02 out to have a look at it. when I got it out it was a whitish yellowish color which i didn't think was good. So I said no more fuel. my buddie gave me a sensor to try and it worked fine, for a day. Took it out same thing whitish color. So for chucks and giggles I stuck an old one that I knew didn't work at all back in, went for a drive came back white. This really got me cunfused and mad. And I'm starting to that the fuel has nothing to do with it. Shouldn't they be black and full of soot? Any help would be great. Gary