What does the flashing green 'S' mean on the dash of a 1991 Honda Accord LX?

I had a similar problem, well mine (S light) flashed occasionally but the "check engine" light was on permanently a lot of geniuses gave their opinion but it was very simple. Replace the oxygen sensor and that will take care of it. Now, that light comes on when you "need" to have a more responsive kind of driving It means Sport driving and to activate or deactivate it, there's a little button on the shift lever, on an automatic car