it reads the mph off each sensor so if its not matching your speed-o id think that one is bad. im not all that sure how good it really is tho, driving straight down the road they all line up and match speed, all but my backs, but sitting still 3 will read 1.6 mph or so, (all different) and one would read 0.0. kinda odd. but a cool thing to check on.
i had to add torque scan to get KR to read, so the abs stuff may have come with that add on.
funny cause i was looking for a app to read abs codes, all ive found so far is U-scan, free app but they want 7 bucks for the abs unlock for your 1 car, or 15 to unlock all of them. not a bad deal really.