5 Symptoms Of A Failing Wheel Speed Sensor

Here are the five signs that indicate a bad wheel speed sensor: 

1. ABS Warning Light Turns On

Most modern vehicles are equipped with an ABS system (anti-lock braking system), traction control, and an electronic stability system to ensure safer braking under different driving conditions. 

The ABS speed sensor (or ABS sensor) is a primary data source for these systems.

If a wheel speed sensor fails, the ABS light, Check Engine light, or the traction control light will illuminate on your vehicle’s dashboard. 

2. Anti Lock Brakes Stop Working

Your vehicle’s ABS control module relies on the speed sensor to determine if the wheels are locking up due to hard braking. 

The ABS module stops receiving this data when a wheel speed sensor fails. Without the speed signals, the ABS controller shuts down the anti-lock brake. 

3. Pulsating Brake Pedal

Each ABS wheel speed sensor measures the wheel’s speed it’s attached to. If a sensor goes bad, it’ll send false data to the ABS control module. This can cause the ABS module to believe that the vehicle is sliding off, and it’ll activate the anti-lock brakes.

When this happens, the ABS will release brake pressure, pumping the brakes rapidly. As a result, your brake pedal will pulsate when you hit it. 

4. Traction Control And Stability Control Stop Working

A failing wheel speed sensor will turn off your vehicle’s traction control, stability control, or any other driver assist feature. Sometimes, a damaged wire could also prevent the sensor from sending data to the control module.

As a result, you’ll find it difficult to maintain traction in poor weather conditions or have frequent braking issues.

If you’re facing issues with any of these features, you should get your ABS wheel sensor checked at an auto repairs shop. 

5. Speedometer Doesn’t Work

This is a rare symptom and usually happens in older vehicles. If you notice that your speedometer isn’t working, it could be due to a bad wheel speed sensor.

A faulty speedometer is also a safety hazard as you won’t know whether you’re driving at low speed or too fast and could put your and others’ lives at risk.

How Much Does An ABS Wheel Speed Sensor Replacement Cost?

Standard replacement parts can cost anywhere between $200 to $400, depending on your car’s model and the labor charges in your area. 

However, an ABS wheel speed sensor on a luxury vehicle can cost more. Moreover, it could be challenging for an auto parts mechanic to work around certain cars, further escalating labor costs. 

It’s also better to replace an old sensor with an OEM sensor, though it’s usually costlier than an aftermarket wheel sensor. 

Here’s why: 

• The exact clip placements and routing are crucial for a sensor’s functioning. 
• The air gap to the tone ring should be exact to read the speed data.
• The wheel speed sensor’s sensitivity depends on precise electrical specifications.

How Urgent Is A Wheel Speed Sensor Replacement?

Technically, you can continue to drive your vehicle with a faulty ABS wheel speed sensor.

However, your vehicle’s safety features like the anti-lock braking system and traction control will not function properly and can jeopardize your road safety.

If you suspect a sensor failure, it’s best to get an ABS speed sensor replaced as soon as you notice any symptom.

5 FAQs On Wheel Speed Sensor

Here are answers to some common wheel speed sensor questions: 

1. What Is A Wheel Speed Sensor?

A wheel speed sensor (also known as an ABS sensor or ABS brake sensor) is a critical part of your braking system. The speed sensor works with the tone wheel to monitor the speed of your vehicle’s wheels and relay the data to the ABS.

The ABS control module reads this data to ensure that all the wheels move at the same speed. Accordingly, it corrects any wheel and brings it to speed. With the help of wheel speed sensors, your car’s ABS can also prevent your wheels from locking up during hard braking.

Additionally, the speed sensors assist the traction control system to gain more control over your vehicle when you’re hitting uneven roads.

However, like any other braking part, the wheel speed sensors are subject to wear and tear. They can get damaged by dust, dirt, etc., and may often need replacement. 

2. Where Is The Wheel Speed Sensor Located?

A speed sensor is usually located on the steering knuckle behind the wheel’s brake rotor. Sometimes it may also be installed directly on the wheel axle.

While most modern vehicles have four sensors (one on each wheel), an ABS system can also have other configurations:

• Two-channel four sensor ABS: An ABS brake sensor is located on each wheel, but the vehicle has one channel for the front sensors and one for the rear.

• Three-channel three sensor ABS: One sensor is located at each front wheel, and a rear wheel speed sensor is installed on the rear axle. The rear wheels are monitored together by the rear sensor, while the front wheels are monitored separately.

• Three-channel four sensor ABS: One sensor is installed on each wheel, but a single controller monitors the rear wheels. 

3. How Long Does It Take To Replace A Wheel Speed Sensor?

Diagnosing sensor failure is pretty straightforward, and replacing it with a new sensor shouldn’t take more than an hour (including the diagnostic time).  

4. How Do I Replace A Wheel Speed Sensor? 

Whether you own a Honda, Chevrolet, or Toyota, replacing a speed sensor as a DIY isn’t difficult. However, you need the right tools and should know your car parts.

Sometimes, you may need to remove certain brake parts like the brake caliper, brake pad, and brake rotor to access the speed sensor. 

If you’re unsure, it’s best to have a professional at your dealership replace the ABS wheel speed sensor for you or get a mobile mechanic to drop by and help you out.

But, if you still plan to do it yourself, here’s how: 

1. Engage the parking brake and disconnect the negative battery cable.

2. Raise your vehicle using jack stands.

3. Use a breaker bar and lug nut socket set to remove the wheel from the wheel hub assembly.

4. Disconnect the electrical connector from the ABS sensor harness.

5. Remove the retaining bolt holding the sensor onto the steering knuckle. Also, remove any fasteners holding the sensor wiring harness in place.

6. Remove the sensor from the vehicle.

7. Ensure that the new sensor has the same design as the old sensor. Preferably, go for an OEM sensor.

8. Install the sensor, and fasten the retaining bolt. Also, reinstall the wheel speed sensor harness.

9. Using a torque wrench, tighten the fasteners and other parts as per the specifications given in the repair manual.

10. Reconnect the ABS sensor electrical connector.

11. Reinstall the brake rotor and brake caliper along with your brake pad if you had removed them earlier.

12. Reinstall the wheel on the wheel hub, and remove the jack stands to lower your vehicle.

13. Reconnect the negative battery cable.

14. Finally, use a scan tool or code reader to clear any ABS codes or other Diagnostic Trouble Codes (DTCs).

5. Why Is My New Sensor Not Working? 

If your wheel’s new sensor isn’t working, there could be some issue with the wheel bearing.

The sensor will only function when it’s at an exact air gap to the tone ring in the wheel bearing. Any misalignment or debris can affect this air gap, causing the new sensor to not work.