7 Symptoms Of A Bad ABS Wheel Speed Sensor | What Causes Wheel Speed Sensor Failure?

The ABS sensor is most commonly used in modern cars. ABS sensor measures the speed of your vehicle wheels. When it goes bad, it produces different problems. The following are the most common symptoms of a bad ABS wheel speed sensor.

The ABS wheel speed sensor plays many important roles. It helps to control the stability and traction of your car. Therefore, it is one of the most important sensors of the vehicle. When it goes bad, it produces different signs. This guide explains the bad ABS wheel speed sensor symptoms, causes, and how to replace it.

Symptoms Of A Bad ABS Wheel Speed Sensor

An illuminated ABS light is one of the common signs of a bad ABS sensor. A bad ABS wheel speed sensor may also lead to reduced traction control, diminished anti-lock brake functionality, and a pulsating brake pedal. Additionally, you might observe other dashboard warning lights, such as the traction control light or check engine light.

The most common symptoms of a bad ABS wheel speed sensor are deeply explained below:

1) ABS Warning Light

The dashboard of your car has different warning lights that tell you if something goes bad. The illumination of the ABS warning light is one of the clear symptoms of a bad ABS wheel speed sensor.

At the start, it might only make the ABS light to activate. As the issue progresses, you may also observe the illumination of the traction and stability control warning indicators.

In uncommon instances, a faulty ABS sensor may lead to the speedometer ceasing to record speed accurately.

2) Loss of ABS

The primary function of the anti-lock braking system (ABS) is to ensure controlled braking by smoothly applying brake fluid, engaging brake pads and calipers to decelerate the vehicle without causing tire lock-up.

The wheel speed sensor plays a crucial role by transmitting wheel speed data to the Electronic Control Module (ECM), allowing the ABS system to determine the appropriate pressure for safe braking. When this sensor malfunctions or operates improperly, it directly impacts the functionality of the ABS system.

When you push the brakes and observe the front tires locking up, it’s imperative to promptly engage a professional for a thorough inspection. This issue poses a safety risk and warrants immediate attention.

If necessary, it’s advisable to discontinue driving the vehicle until a mechanic can diagnose and rectify the ABS system issues. Ideally, a faulty ABS wheel speed sensor could be the root cause, necessitating a straightforward replacement.

3) Pulsating Brake Pedal While Braking

The ABS sensors of your vehicle are responsible for gauging how fast each wheel is going. If one of these sensors becomes faulty, it might show the wrong speed for a wheel.

As a result, the traction control module might be deceived into interpreting the vehicle as skidding on a slick surface. This issue will prompt the activation of ABS and traction control mechanisms, noticeable through a pulsating or undulating brake pedal sensation during braking.

4) Loss of Traction Control

The loss of traction control is also one of the clear signs of a bad ABS wheel speed sensor.

A bad ABS sensor doesn’t just affect anti-lock brakes but also affects other important functions like hill-start assist, roll stability, traction control, and stability control. When the wheel speed sensor stops sending information, the vehicle’s ABS control module stops working of these associated systems.

Nonetheless, issues can arise even without the illumination of the ABS light. Challenges with maintaining traction under adverse weather conditions or observing compromised control during sudden braking could potentially indicate a fault with the ABS sensor.

Another potential factor could involve impaired wiring connections spanning from the sensor to the Engine Control Module (ECM).

5) Instability While Braking

During normal functioning, the ABS system engages during forceful braking to promptly decrease your car’s speed, preventing brake lock-up and potential skidding.

The ABS sensor employs the data it collects to fine-tune brake pressure, ensuring avoidance of lock-up and maintaining traction in critical braking conditions. This significance is particularly evident on slippery surfaces like icy or wet roads, where the challenge of averting brake lock-up and skidding is heightened.

6) Brakes Take Longer To Stop The Vehicle

During aggressive braking, the ABS system of a car is designed to activate itself, effectively reducing skidding and preserving traction. Cultivating a consistent driving practice that averts abrupt braking situations is advisable.

If your car exhibits prolonged braking intervals during forceful braking, accompanied by loss of traction or skidding, it could signify an anomaly within your ABS system.

When the ABS wheel speed sensor of your vehicle becomes faulty, the vehicle takes a large time to slow down or stop. A defective sensor has the potential to give rise to braking complications.

7) Unusual Noises

A bad ABS wheel speed sensor may lead to unusual noises, such as clicking or grinding noises, especially while braking. These sounds may indicate wrong sensor readings affecting the operation of the ABS system.

Causes Of A Faulty ABS Wheel Speed Sensor

The ABS sensor of your car may go bad due to one or more of the following causes:

Manufacturing fault
Poor installation of the sensor
Poor maintenance
The buildup of debris, road salt, mud, or dirt on the sensor
Your sensor can be damaged due to impacts from accidents, curbs, or road hazards
Normal wear and tera
Excessive temperatures and severe environmental conditions may lead to ABS sensor failure

ABS Wheel Speed Sensor Function

The ABS wheel speed sensor is also referred to as a wheel speed sensor or ABS sensor. Regardless of its name, it plays a big role within the ABS system.

Present in the majority of modern cars, the ABS system contains ABS wheel sensors connected to the axle or wheels. These sensors determine the rotational velocity of the wheels.

Many ABS sensors comprise a toothed ring and a magnet surrounded by a coil. An interaction between the ring and magnet generates an electric field, ultimately translating into electrical signals. These signals are transmitted to the ABS controller.

Subsequently, the ABS controller evaluates the speed of each wheel and sends this data to the ECM. Upon detecting a wheel lock-up, the ECM activates the ABS. This operation unfolds rapidly, often accompanied by a grinding sound and a pulsating sensation.

In situations where a vehicle is furnished with traction control, the ABS sensor aids in managing vehicle movement during risky scenarios. If traction is compromised and one wheel’s speed diverges from the others, the system intervenes.

The ECM arranges a reduction in braking force applied to the affected wheel, a measure designed to counteract issues. As this force reduces, the wheel regains traction, restoring regular rotation. These sensors are also integral to the operation of stability control systems found in contemporary automobiles.

ABS Wheel Speed Sensor Location

The ABS wheel speed sensor is positioned close to the wheel, either directly on the axle or behind the brake rotor. The number of ABS sensors varies depending on the vehicle.

In instances where a system encompasses four ABS wheel speed sensors, each wheel will be equipped with one sensor installed behind the rotor. In vehicles with three sensors, there’s one sensor on each of the front wheels, and the third sensor is on the back axle, not on either of the back wheels.

The number of ABS sensors is contingent upon the ABS type implemented in the vehicle. Four distinct ABS configurations are discussed below.

Three-channel, four-sensor ABS: All wheels have sensors, but the back wheels share a controller.
Two-channel, four-sensor ABS: Each wheel has a sensor – one set for the rear wheels and another for the front. If a sensor detects wheel lockup, ABS activates for that part of your car.
Three-channel, three-sensor ABS: In this configuration, a sensor is placed on each front wheel, and one is on the back axle. The rear wheels are observed together, while the front wheels are assessed individually.

How Do I Replace An ABS Wheel Speed Sensor?

Follow the below-given steps to replace the faulty ABS sensor:

Put on the parking brake.
Switch off the engine and let it cool.
Don’t start working until your engine is cold down.
Remove the negative battery cable to prevent yourself from electric shock.
Use a jack to elevate the car and put jack stands under it.
Take off the wheel from the wheel hub assembly by using a lug nut socket set and breaker bar.
Disconnect the ABS sensor harness by unplugging the electrical connector.
Unfasten the retaining bolt securing the sensor to the steering knuckle. Additionally, remove all bolts securing the sensor wiring harness in its position.
Gently remove the faulty sensor from your car.
Buy a new sensor suitable for your car. Opt for an OEM sensor if possible.
Connect the new sensor in the vehicle, secure the retaining bolt, and reattach the wheel speed sensor harness.
Following the instructions outlined in the owner’s manual, tighten the bolts and other components by utilizing a torque wrench.
Connect the electrical connectors back to their original positions.
Reinstall the brake pad, brake caliper, and brake rotor if previously removed.
Mount the wheel onto the wheel hub and lower the car by removing the jack stands.
Reconnect the negative battery cable.
Finally, use a scan tool or code reader to clear any ABS codes or other Diagnostic Trouble Codes (DTCs).

ABS Wheel Speed Sensor Replacement Cost

The replacement cost of the ABS sensor depends on your vehicle model and the labor cost. The average replacement cost of an ABS wheel speed sensor is from $180 to $420.

For the sensor itself, you might pay roughly $80 to $160, and then the labor cost could be from $100 to $260.

Labor Cost	$100 to $260
ABS Sensor Cost	$80 to $160
Total Cost	$180 to $420

FAQ Section

Can you drive with a bad ABS sensor?

You can drive with a messed-up ABS sensor, but it’s risky. Your anti-lock brakes might not do their job properly. Safety is most important, so it’s better to get it fixed soon.

Can ABS sensors be cleaned?

Yes, you can clean your ABS sensor, but it may not restore the issue. An ABS sensor usually fails due to electrical problems. Yet, if the ABS reluctor ring is rusty, it can send the wrong information.

Can ABS sensors cause transmission problems?

In some car models, a bad ABS wheel speed sensor may affect the performance of the transmission. That’s why a few vehicles might go into limp mode to protect the transmission.

Does the ABS sensor affect acceleration?

It’s rare, but yes. ABS sensors also help with traction control. If a sensor sends incorrect information, your vehicle’s main computer may reduce engine power to keep things safe.

How to tell which ABS sensor is bad without a scanner?

To check an ABS sensor without a scanner, inspect the sensor visually. Inspect the connections and wires connected to the sensor for disconnection, corrosion, or damage. Additionally, you can use a multimeter to test the resistance of each sensor.

What happens when a wheel speed sensor goes bad?

When an ABS sensor becomes faulty, it may transmit incorrect information to the ABS control module. Consequently, the module might interpret the situation as if the vehicle is skidding and initiate anti-lock brake activation. This action prompts the ABS to rapidly discharge brake pressure, resulting in a pulsating brake pedal motion.

What causes wheel speed sensor failure?

A wheel speed sensor can become faulty due to different reasons such as the corrosion, manufacturing defects, poor maintenance, wrong installation, harsh environmental conditions, low-quality sensor, faulty tone ring, and normal wear and tear.

How to turn off ABS Light?

In many cases, the ABS light itself turns off as the main problem is fixed. If it remains illuminated, utilizing a diagnostic scanner should enable you to clear the saved codes and turn off the ABS light. Should the underlying issue persist, there’s a high probability that the ABS light will reappear soon.

Written By

Professor Shakeel

Professor Shakeel is an automotive expert. He has been working as a car mechanic for over 6 years. As a content writer, he aims to simplify the most challenging concepts for his readers and help them self-diagnose what may be wrong with their cars.