When a wheel speed sensor is giving erratic speed reading or is no longer generating a signal, several things happen. First, the ABS will be deactivated and the ABS MIL will illuminate in the instrument cluster. Also, a code will be stored indicating which wheel has failed and the performance issue of the sensor.
In this video, Andrew Markel walks through a common wheel bearing failure and the resulting codes.
This video is sponsored by BCA Bearings.