C0024
Front Left ABS Wheel Speed Sensor Signal Malfunction
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The C0024 code indicates that the ABS control module has detected a problem with the signal from the left front wheel speed sensor. This sensor is a small electromagnetic or Hall-effect device mounted near the wheel hub that monitors how fast the left front wheel is spinning. The ABS module uses this information, along with data from the other three wheel speed sensors, to detect wheel lockup during braking and activate anti-lock braking as needed.
With this code active, your regular brakes will continue to work normally. However, the ABS system will likely be disabled, which means your wheels could lock up during hard braking on slippery surfaces. Traction control and electronic stability control may also be disabled since they rely on wheel speed data to function. You may notice the ABS and traction control warning lights on your dashboard.
This is a relatively common issue, especially on vehicles with higher mileage or those driven in harsh weather conditions. Start by visually inspecting the sensor and its wiring at the left front wheel — look for obvious damage, corrosion, or disconnected plugs. Wheel speed sensors are typically bolt-on parts that are straightforward to replace, making this a good DIY repair if you're comfortable working on the wheel area. If the sensor looks fine, the tone ring on the hub or CV axle should be inspected for damage.
Severity
Symptoms
- •ABS warning light illuminated on the dashboard
- •Traction control or stability control warning lights on
- •ABS activating unexpectedly at low speeds or on dry pavement
- •Slight pull to one side during hard braking
- •Cruise control may not function on some vehicles
Likely Causes
The wheel speed sensor mounted at the left front wheel hub can fail internally due to heat exposure, moisture intrusion, or physical damage from road debris. A failed sensor produces no signal or an erratic signal that the ABS module cannot interpret.
The wiring that runs from the ABS module to the left front wheel area is exposed to road spray, salt, debris, and suspension movement. Over time, the insulation can crack, wires can break, or connectors can corrode, interrupting the signal.
The toothed tone ring that the sensor reads can become cracked, chipped, or clogged with metallic debris from brake dust. Missing or damaged teeth cause irregular signal patterns that the ABS module interprets as a fault.
The gap between the sensor tip and the tone ring must be within a tight tolerance. Worn wheel bearings, improper sensor installation, or a bent sensor mounting bracket can increase this gap, weakening the signal below the detection threshold.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Replace the left front wheel speed sensor
- Repair or replace damaged wiring and connectors
- Clean or replace the tone ring (reluctor ring)
- Replace worn wheel bearing assembly that includes an integrated tone ring