You just helped out a bunch of people thanks for the info! One of the most surprisingly easy things to do to save a bunch of cash is to do your own brakes. There are several good "how to" videos on YouTube. BavAuto has a very good one and there parts are cheap, that's where I got mine. And for those who may not know I'll repeat the, perhaps, obvious. There is a an "eye" hole to look through your caliper to check the wear on the pad and to get specific you could measure it. But most mechanics eyeball it unless it is obvious in need of changing. So, for those wondering how much time you have until you HAVE to change your brakes after the sensor comes on, just pull your tire off and look for yourself. But at that point, you may as well change your brake pads while your at it, because your basically half way done already!