On modern cars the ABS system is also tied in with other features and systems. ABS sensors are used for speedometer readings, traction control, stability control, and other components. So when a sensor fails it's not just affecting your braking but cascading through the rest of the car as well. Typically there will be an ABS light on in the dash cluster but the SES/CEL light may also come on which will require a trip to the dealer to have the fault analyzed.
There are other components of the ABS system that are common failure or known weak points - control modules, pressure sensors, and relays. We keep in stock many of the parts that are prone to common failures, allowing you to get safely back on the road in short order.