ABS Sensor Buying Guide
Last updated: 24 April 2026
ABS wheel speed sensors monitor the rotational speed of each wheel, providing data to the ABS, ESC, and traction control systems. A faulty sensor triggers warning lights, disables these safety systems, and can cause the speedometer to malfunction. At CarParts247 we stock ABS sensors from Bosch, ATE, and Delphi.
ABS sensor fault symptoms
When an ABS sensor fails, the ABS module loses data from that wheel and deactivates the safety systems. The ABS and ESC warning lights illuminate on the dashboard.
- ABS warning light on the dashboard — sensor signal lost or erratic
- ESC/traction control warning light — these systems depend on ABS sensor data
- Speedometer reading zero or fluctuating — some vehicles use ABS sensors for speed
- ABS activating unexpectedly at low speed — erratic sensor signal
- Diagnostic codes C0035-C0050 (wheel speed sensor circuit)
Reluctor ring inspection
The ABS sensor reads a toothed reluctor ring (tone ring) mounted on the hub, driveshaft, or inside the bearing. A damaged or corroded reluctor ring causes the same symptoms as a faulty sensor.
- Inspect the reluctor ring for damaged, missing, or corroded teeth
- Magnetic sensors: check the sensor tip for metallic debris buildup
- Active sensors (with built-in electronics): check the wiring and connector for damage
- Measure the air gap between the sensor and reluctor ring — too large causes signal loss
- Some reluctor rings are integrated into the wheel bearing — replacing the bearing replaces the ring
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ABS and ESC warning lights — wheel speed sensor diagnosis, reluctor ring checks, and replacement guide.
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Frequently Asked Questions
Can I drive with the ABS light on?
Yes, normal braking still works. However, ABS, ESC, and traction control are disabled, meaning reduced safety in emergency braking and slippery conditions. Fix the fault promptly.
How do I diagnose which ABS sensor is faulty?
Use an OBD diagnostic scanner that reads ABS codes. The code identifies the specific wheel. You can also compare live data readings from all four sensors — the faulty one will show zero or erratic readings.
What is a reluctor ring?
A toothed ring that the ABS sensor reads to determine wheel speed. It is mounted on the hub, driveshaft, or inside the wheel bearing. Damaged or missing teeth cause erratic ABS sensor readings.
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