ABS sensor is a type of tachometer that measures the rotational speed of a wheel and passes it to the car's Engine Control Module.

The ABS sensors should be replaced when some signs are noted from the car. A faulty ABS is indicated by a light on the ABS system. When this light is seen, there is an indication that the system is faulty. Another indicator of the need to replace this system is indicated by the failure of brakes to stop a car as well as less stability of a vehicle in icy or wet regions.