How to Tell Which ABS Sensor is Bad in 2022 – Flawless Car Guide

how to tell which abs sensor is bad

Though car accidents are thankfully becoming less frequent, they still happen. When they do, it’s important to have the right protection in place. One of the things you can protect yourself against is car ABS.

ABS, or an anti-lock braking system, is a safety feature that helps prevent accidents by reducing the risk of skidding and spinning. ABS is standard equipment on many new cars. It works by detecting when the car is going too fast for the conditions and uses friction brakes to stop the car.

If your ABS light is on, it means that your ABS system is malfunctioning and that you should expect your wheels to lock up when you try to slow down. As a result, it is vital that this problem be resolved as soon as possible.

In this article, we’ll discuss how to tell which ABS sensor is bad and more. So let’s get started:

If One Fuel Injector Is Bad Should I Replace Them All? 2022 Ultimate Guide

How to Tell Which ABS Sensor Is Bad?

Before we start abs sensor testing, It is critical to understand bad abs sensor symptoms, abs sensor location, ABS sensor function, and its replacement cost:

Bad ABS Sensor Symptoms:

When it comes to the braking system in your car, it wouldn’t be complete without ABS sensors. Because they tell the car’s computer how much braking pressure each wheel needs, they play a critical role in your safety. A malfunction in your ABS sensor can result in a catastrophic disaster. There are, however, a few warning signs that can assist prevent an accident from occurring if you take action early enough. The following are some of the most typical a bad abs sensor symptoms:

how to tell which abs sensor is bad

Glowing Warning Lights:

The lights on your dash are designed to alert you to potential hazards. When your car’s ABS light comes on, it’s important to take it seriously. This light is an indication that there is a problem with the anti-lock braking system. When this system is not working properly, it can cause the brakes to lock up and the car to skid. If this happens, you could lose control of the car and be in danger of crashing.

In the beginning, you may see the ABS warning light come on. If other systems fail, traction and stability control warning lights may also come on. If the ABS wheel speed sensors are failing, the speedometer may stop operating.

If your ABS light comes on, there may be something wrong with the abs sensor or another part of the anti-lock braking system.

Brake Pedal Pulsation While Braking:

When you brake, do you feel a pulsing in your foot? If so, it could be a sign that your brake abs sensor is bad. Wheel speeds will be recorded erroneously if one or more of the vehicle’s ABS sensors go out.

A false reading from ABS will cause a car to slide since it will be misled into believing that it is sliding on the ground when it isn’t. When this happens, the ABS and traction control trigger out, and the brake pedal will pulsate or pump.

Loss Of Anti Lock Brakes:

When the ABS sensor stops working, the anti-lock brake system is also disabled. This means that the car will not be able to pump the brakes for you as you brake, which can cause your car to skid. When a problem is detected, the system sends out a signal and illuminates the ABS warning light.

An electronic control module is required to prevent the sensor from transmitting crucial data. The computer relies on this information to determine if the wheels are stuck and need assistance. The vehicle’s Anti-Lock Brake System (ABS) is disabled until it can be repaired.

Stability Control Failure or Lack of Traction:

Stability control systems can be dangerous if drivers aren’t aware of the risks. They are designed to help drivers keep control of their vehicles in adverse weather or icy situations, but they can potentially fail. Failure of the vehicle’s stability control system can cause traction loss and, in some situations, a collision.

There are several potential causes of a stability control failure, but one of the most common is a bad abs sensor. This sensor is responsible for sending information to the car’s computer about the status of the brakes. If this sensor is not working correctly, it can cause the stability control system to fail. Defected wiring from the sensor to the ECM could also be to blame.

If you experience any of these symptoms, your ABS sensor may malfunction. The best way to determine if this is the case is to know how to check abs sensor. If it turns out that you have got a bad abs sensor, it will need to be replaced.

How to Fix Car Roof Lining Without Removing | 5 Easy Ways

how to tell which abs sensor is bad

ABS Sensor Location:

It’s common to find the ABS sensor beneath the brake rotor, but it’s possible to find them on the axle as well. Different cars have different percentages of ABS wheel speed sensors.

If the system includes four-wheel speed sensors, then an ABS wheel speed sensor is installed on each rotor. A system with three sensors has two sensors on each front wheel and one on each rear axle, instead of having one sensor on each wheel.

The number of sensors in a car is determined by the type of ABS it has. Here are four different ABS sensor location combinations.

  1. A two-channel, four-sensor layout ABS: Each wheel has a sensor, but the sensors are separated into two channels, one for the front and another one for the back. Antilock braking systems (ABS) are engaged when any speed senses a wheel malfunction.
  2. At every front wheel and the rear axle, there is a 3-sensor anti-lock braking system (ABS). In contrast to the rear wheels, the front wheels are evaluated independently.
  3. Three channels and four sensor systems: The rear wheels are controlled by a single controller, even though sensors are located on every wheel.
  4. Four-wheel ABS: Each wheel has its sensor, which is scrutinized individually. With newer cars, this is by far the most popular setup.
how to tell which abs sensor is bad

ABS Sensor Function:

Also known as an ABS brake sensor, the wheel speed sensor is a common abbreviation for the ABS brake system. The ABS wouldn’t be complete without it.

Anti-lock brake systems are standard equipment on the majority of new vehicles (ABS). ABS wheel sensors, which are attached to the wheels or the axle of your vehicle, measure the rotational speed of your vehicle’s wheels.

A shaft ring and magnet are surrounded by a coil in most ABS sensors. The signal sent to the ABS control system is generated by the electric field created by the interaction between the magnet and ring.

For each individual wheel or axle, the speed is determined by the control system. The received information is processed by ECM (Engine Control Module).

As a safeguard against a wheel lock, the ECM turns on the ABS. Since it runs at such a high speed, the machine makes a grinding noise and vibrates constantly.

Traction control and the ABS sensor work together to keep the vehicle in control under unstable situations. When traction is lost, the system will be able to activate since one wheel’s speed will be different from the others.

To make matters worse, the computer lowers the brake force applied to the wheel. When this force is decreased, the wheel can restore grip and continue the regular rotation. The same sensors are used in the stability control systems of high-end cars.

how to tell which abs sensor is bad

The Price of a New ABS Wheel Speed Sensor:

According to the make and model of the vehicle, the cost of replacing a bad ABS sensor ranges from $200 to $400 per sensor. Between $100 and $150 is the cost of the wheel speed sensor, and between $100 and $300 is the cost of the work.

Adding ABS wheel speed sensors to exotic vehicles may get pricey, and because some models are more difficult to repair, labor expenses go up as well.

You can easily replace the ABS wheel speed sensor on your own with a few simple tools. With some mechanical know-how, this could be an interesting project to work on in your garage. However, if you don’t have the proper training, you won’t be able to complete this project on your own.

how to tell which abs sensor is bad

How to Test ABS Sensor Using Tools:

A scan tool for vehicles is necessary to determine which ABS sensor is failing. Simply plug in the device, choose your vehicle’s model, and then click Diagnose ABS to see the error codes indicating which speed sensor has failed.

Likewise, you can use a multimeter or a voltmeter, but you’ll need to locate your ABS sensor and disconnect its cables before you test the ABS wheel speed sensor.

Steps for ABS Sensor Testing:

  1. Connect your chosen scan tool to your vehicle after ensuring that it enables ABS sensor testing with your scanner of choice. On the main screen, click Diagnostics, then select the make and model of your car. Finally, choose System Selection and allow the gadget to establish a connection with the car.
  2. Wait for the diagnostic system to initialize, which takes a few minutes. Select ABS VSA from the Control unit and wait for the system data to load before driving. The tool will reveal any fault codes it finds if you pick read Codes from the Codes menu.

The code that will appear explains that the speed sensor on the left rear wheel is monitored by the ABS Module. If the sensor signal return circuit is shorted to ground or open, this could indicate a short or open in the sensor itself, or if the sensor has an inner short or open. Many other flaws are triggered as a result of the fault code.

how to tell which abs sensor is bad

Multimeter or Voltmeter:

A simple multimeter test can be used to examine the wheel ABS sensors if a scan instrument is not available. This procedure may necessitate some knowledge of the fundamentals of auto repair. You’ll need to be able to remove the wheel to check the ABS sensors.

Steps for ABS Sensor Testing Using Multimeter:

  1. The car should be parked on level ground. The engine should be shut down. There is a handbrake on, so you can easily slow down or stop at any time. The ABS filament should be present in your car’s main fuse box. The fuse needs to be replaced.
  1. Unscrew the lugs on your wheels with a tire iron. Then, jack up the car and put it on a pair of good jack stands. Remove all the lug nuts with the tire iron and put them away. 
  2. Look for the wheel speed sensor wires under the brake disc and make sure they are not damaged. A sensor is located on the rotor. With your hands, pull the wires apart from each other. The two-pin connector may be seen.
  3. Connect the voltmeter’s probe to an ABS sensor connector in the next step. In order to see how much electricity is coming in from the opposite way, you’ll need to flip the voltmeter over (AC). Make sure the probes aren’t rubbing against each other.
  1. Turning off the voltmeter is the first step toward getting it to operate. You can begin testing as soon as the computer recognizes this message. To check the ABS sensor, just rotate the wheel hub with your hand. Slow rotation is the best strategy. There will be reading on the voltmeter because of the revolving hub’s charge.
  2. An accurate value should be approximately 400 volts, provided the sensor is functioning. The speed at which you spin the hub will affect the reading, which will vary based on the vehicle.
  3. A correct reading on one sensor means you can go to the next.

Methods for Getting an Accurate Reading:

The ABS reluctor is a gear with teeth that can be found behind the wheel. The teeth must be present and undamaged. Test the ABS sensor once more after cleaning up any metal particles.

how to tell which abs sensor is bad

Frequently Asked Questions:

Q: How to Tell Which ABS Sensor is Bad?

A: The ABS or traction control light on the dashboard of the car may illuminate if the ABS sensor is malfunctioning. Another symptom of a faulty wheel speed sensor is a significant loss of traction when driving on slick roads.

Q: What are the Bad ABS Sensor Symptoms?

  • When the ABS fails, this is the most prevalent among the bad abs sensor symptoms.
  • During hard braking, the ABS is meant to prevent any wheel from locking up.
  • A Brake Pedal That Isn’t Responding.
  • Intensified Effort on the Gas Pedal.
  • The speedometer is faulty.

Q: What happens if the ABS sensor is disconnected?

A: When braking at high speeds, the rear brakes can lock up before the front ones, which can result in a loss of stability. If you find that unplugging the sensor fixes the problem for you, don’t be deceived. Simply by turning off ABS altogether, you’ve managed to hide the problem.

Q: Is there a Noise When the ABS Sensor Fails?

A: A crushing or vibrating sound may be heard from the ABS controller. You may notice a little vibration in some vehicles. When you hear sound or experience pulsations, keep your foot on the brake pedal.

Q: What causes the malfunction of a speed sensor?

A: Common reasons for failure include the following. A common cause of sensor failure is clogging from metal particles, brake dust, or dirt caused by exposure to harsh conditions.

Q: Can I drive with an ABS Light On?

A: In general, driving a vehicle with a malfunctioning wheel speed sensor is dangerous. Car computers aren’t able to tell you how fast you are going, so they may apply the brakes too quickly or enhance engine performance.

Q: A wheel speed sensor can cost how much to replace?

A: The cost of replacing an ABS wheel speed sensor ranges from $200 to $400 per sensor, based on the make and model of the vehicle and the labor costs involved. The wheel speed sensor costs between $100 and $150, and labor costs between $100 and $300.

On exotic cars, ABS wheel speed sensors could indeed cost extra, and some models are more difficult to work on, which raises labor costs.


In conclusion, if you are experiencing problems with your abs system, there are a few things you can do to help determine which sensor is bad. 

Using a car diagnostic tool, it is simple to identify which ABS sensor is malfunctioning. If you don’t have access to a diagnostic tool, the simplest method is to use a multimeter. We’ve walked you through the process of determining which ABS sensor is malfunctioning in this guide.

Invest in a car scanner or multimeter and gain knowledge of how to utilize it to save money on diagnostics at repair shops. In addition to ABS, they can be used to identify other issues with a vehicle.

Leave a Comment