I think you mean "box" rather than "open end". (I would be hesitant about using an open end wrench on an O2 sensor. I think it might round the corners.) That's how I did mine, too. I've been told that in some cases clearance is an issue and that the 22mm box won't work (though it did on my 1985 B230F) in which case a 22mm flare nut crowfoot is called for. I'm told you can get such a thing fromn autozone for about $15.

Harold