What Is a ABS Wheel Speed Sensor?
The ABS wheel speed sensor is a small electromagnetic or Hall-effect sensor mounted at each wheel, typically integrated into or mounted adjacent to the wheel bearing. It monitors the rotational speed of a toothed ring (tone ring) on the wheel hub, generating a signal that is continuously monitored by the ABS control module. Modern vehicles also use these sensors for traction control (ASR), electronic stability control (ESP), and in some cases cruise control and speedometer operation.
What Does the ABS Wheel Speed Sensor Do?
The ABS system uses wheel speed data from all four sensors to detect when one or more wheels are about to lock under heavy braking. When lockup is detected, the system rapidly modulates brake pressure to that wheel — allowing the driver to maintain steering control while braking at maximum effectiveness. Without functioning wheel speed sensors, ABS, traction control and stability control systems are disabled.
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Get My Free Fault Scan →Symptoms of a Failing ABS Wheel Speed Sensor
A faulty ABS sensor causes the ABS warning light to illuminate on the dashboard — which is an automatic MOT failure. If the stability control system also uses the sensor, additional warning lights may appear. Some vehicles enter a reduced braking mode when an ABS fault is detected. The sensor itself, its wiring, or the tone ring can all cause the fault code.
When Should the ABS Wheel Speed Sensor Be Replaced?
ABS sensors are replaced on failure. Corrosion of the sensor connector and damaged wiring from road debris are common causes of failure. The integrated sensor/bearing unit on many modern vehicles requires complete hub bearing replacement. Standalone sensor replacement costs £60 to £180; hub bearing with integrated sensor costs £150 to £350.
If you are experiencing symptoms related to your abs wheel speed sensor and are unsure whether it needs replacing, a free MotorLoom fault scan can help identify whether the component is likely at fault - giving you the most likely cause and estimated repair cost before you visit a garage.
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Related Parts
Other components that work alongside or are related to the abs wheel speed sensor: