Can I drive with an ABS warning light on?

Yes, but the ABS, traction control, and ESP are all disabled. The brakes themselves still function normally. Fix the sensor promptly to restore full safety system operation, especially before winter driving.

How do I know if the sensor or the wiring is faulty?

Flex the wiring harness between the sensor and the ABS module connector while watching live data on an OBD-II scanner. An intermittent signal drop during flexing confirms a wiring fault rather than a sensor fault.

Do I need to replace the reluctor ring as well?

Only if teeth are missing or damaged. A complete ring with no missing teeth that is clean and undamaged will work correctly with a new sensor. Inspect it carefully before reassembling.

Are front and rear ABS sensors interchangeable?

Generally no — front sensors are calibrated for the steering geometry and may differ in cable length and connector type from rear sensors. Always specify front or rear and the correct side when ordering.

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Speed / RPM Sensor buying guide — what to know before you buy

The speed/RPM sensor — also known as the ABS speed sensor, wheel speed sensor, or RPM sensor — monitors the rotational speed of each wheel hub, providing data for the ABS, traction control, ESP, and adaptive cruise control systems. Unlike the gearbox-mounted vehicle speed sensor, these sensors read from a toothed reluctor ring at each hub or drive flange. A faulty sensor triggers ABS and ESP warning lights and disables the associated safety systems. CarParts247 stocks OEM and aftermarket wheel speed sensors from Bosch, Continental, and Hella to cover all four positions across a broad range of vehicles.

How ABS wheel speed sensors work

Active sensors use the Hall effect to produce a digital square wave signal whose frequency increases with wheel speed. Passive (variable-reluctance) sensors produce an analogue AC signal. Modern vehicles almost exclusively use active sensors, which operate down to very low speeds and can also detect the direction of rotation on some platforms.

Active (Hall effect): digital output, works from near-zero speed, three-wire connector
Passive (VR): analogue AC output, minimum speed threshold before signal is valid, two-wire connector
Integrated sensor ring: some hubs have the reluctor ring pressed into the inner bearing seal — replacement requires a new bearing assembly

Failure symptoms and diagnosis

A single faulty wheel speed sensor is the most common cause of ABS and ESP warning lights. The fault code will identify which corner is affected. Inspect the wiring harness at the affected wheel — road debris, heat, and flex fatigue cause harness damage more often than sensor element failure.

ABS warning light on — check codes to identify which wheel
ESP or traction control warning light on
ABS activates unnecessarily at low speed — sensor reading noise
Speedometer affected if the VSS has failed and the system relies on wheel speed input
Reluctor ring teeth visible damage — inspect with a mirror when the sensor is removed