I was driving today and noticed my abs light was on, I never seen this before and dont seam to be any reason for it to be on. Brakes seem fine. Anyone know what can cause this and a fix for it? Could it be a sensor and if so how hard is it to replace?

I also have the OEM brakes and 70,000 miles on the car but i checked a few weeks ago and still have some meat on them.

adam