ABS light on/off

my ABS light came on the other day while i was driving, then went out again. it's been intermitting since. but mostly it has stayed on. i tried disconnecting the battery to try to get it to reset and stay off, but it didn't work. can the dudes at autozone hook up to my computer and tell me if it's throwing a code? am i looking at an expensive fix or could it be a dirty sensor? i praying for a dirty sensor. i've heard horror stories about ABS replacement.

 

no,autozone cant check it.take to the dealer,sorry.

 

What ended up being the issue, how did you fix it?