I've had my IS for over a year now, and the EML has been on pretty much all of that time. (Yes, I'm a bad man, I know I know...) I had it reset twice and it stayed off for about two weeks (not a lot of driving was done in this time though), but eventually came back on again. I think the code was catalyst on bank one below efficiency threshold or something similar - it's quite a common one anyway.
This, plus the blue smoke on cold start ups indicated worn valve seals to most people I've talked to, including a few on here.
But then today, driving home I refuelled and accidentally put super unleaded in, something that I have never done before with my IS. After a couple of miles, the EML turned off! And stayed off for the 80 miles I was driving home for! I waited until it was cold and then started it up and drove it around for a few miles..........no blue smoke on start up, and still no EML!
Now, I'll check to see that the sodding thing hasn't just burned out just because it's been on for so long, but if not, has anyone else experienced anything similar? I usually don't bother with super unleaded but I might try it for a while if these are the kind of things that happen!