How to Tell Which ABS Sensor Is Bad (Expert Guide)

Do you want to know how to tell which ABS sensor is bad? If so, you are on the right page.

In a vehicle, the anti-locking braking system is essential. ABS means an anti-locking braking system, and whenever you are stopping your vehicle, it is the ABS that prevent the brakes from being locked up.

Anytime the anti-locking brake system light comes on, it implies that the ABS would not function, which can cause the wheels to lock up if you try stopping your car.

This is why it’s vital to resolve the issue immediately. If the light comes on, use the Bluetooth OBD2 scanner to search for the error code. You can see the full list here.

This article will explain various methods on how to tell which abs sensor is bad and needs replacement. It will also talk about the things that prevent the ABS light from turning on after replacement has taken place and lots more.

You can make use of a voltmeter or a multimeter also, but you have to find the anti-locking braking sensor and detach the wires.

Also Read: What Is ABS Sensor & Why ABS Sensor Light Comes On?

Where Are the ABS Sensors Located?

You can find the ABS sensor on the wheels. One is on the front right wheel, another on the front left wheel, another on the rear right wheel, and another on the rear left wheel.

The function of the sensor is to keep watch on the wheel’s speed, and if the wheel starts to skid or slip, it sends a warning to the anti-locking braking system controller.

How to Tell Which ABS Sensor Is Bad Using a Diagnostic Tool?

How to Tell Which ABS Sensor Is Bad Using a Diagnostic Tool

Step 1: Join any of the auto diagnosis devices in the car. ( Ensure the device acknowledges ABS scanning)

Step 2: Press the diagnostics that are on the screen, after which you select the model of the car. Then choose system selection and allow the tool to establish communication with your vehicle.

Step 3: Select the geographical area( for example, USA), then stay put till the diagnostic system engages.

Step 4: The next step is to press down the control unit and choose the ABS & VSA, then allow the data of the system to load.

Step 5: Select read codes, and then the device will display the error codes.

If the diagnostic tool displays a C0037 code, it simply means that the ABS module monitors the left rear wheel speed sensor. To be more specific, the C0037:14 implies that the sensor has an internal open or internal short to ground, or there’s an open or short to ground in the sensor return circuit.

The error code also initializes several faults, for example, the left rear electric parking brake actuator, steering angle sensor, etc.

Step 6: Replace or fix the damaged sensor to eliminate the error codes and lights displayed on the dashboard.

On the other hand, to scan codes, you can make use of the OBD2 scanner. Some of the scanning equipment tends to have the ability the read SRS/ABS fault codes since not all can do that. Observe which diagnostic equipment is available and if it’s suitable for your need.

How to Tell Which ABS Sensor Is Bad Using a Voltmeter or Multimeter?

How to Tell Which ABS Sensor Is Bad Using a Voltmeter or Multimeter

If the scanner is not available, you can make use of a multimeter to know the voltage on the wheel anti-locking brake sensors.

You will need a pair of ramps or a lift, for this method means you’ll require fundamental knowledge of car repair. You have to test the anti-locking brake sensors by removing the wheel.

Step 1: Pull your car over a ground level, and switch off the engine. Then press your emergency brake.

Step 2: Replace the fuse if it is blown. Find the fuse block of your vehicle and ensure the fuse filament of the ABS is still in good condition.

Step 3: Use the tire iron to lose the wheels lug. After that, lift your car and use a pair of jack stand which is of nice quality to support it. Using the tire iron, remove the lug nuts completely and separate them.

Step 4: Observe under the wires of your wheel speed sensor and the brake disc. You will see the sensor on the rotor. Then disconnect the wires using your fingers to pull them apart. Examine the two-pin connector.

Step 5: The next step is to press the voltmeter probes against the sensor connection. Switch the voltmeter on and adjust it to AC( alternating current). To obtain an accurate measure, ensure the probes are not touching.

Step 6: Whenever you turn the voltmeter on, the reading should be zero. As soon as your system reads zero, you can go ahead with the test.

Step 7: Use your hand to twirl the wheel hub to test the ABS sensor. Slowly rotate it. The hub will generate a charge that the voltmeter can read. The reading should be about 400 volts if the sensor is functioning well. The reading depends on the speed at which the hub is spinning, and this varies; it also depends on the type or model of the vehicle.

Step 8: As soon as you get an accurate reading for the first sensor, go to another sensor.

How to acquire accurate reading:

  • Look for a gear with teeth called an ABS Reluctor behind the wheel
  • Ensure the teeth are complete and no one is damaged.
  • Clean all the metal shavings and then retest the ABS sensor.

How to Test an ABS Sensor

There are some things you have to be mindful of when you’re testing the ABS sensor.

  1. Before you start, ensure you cut off the power connected to the sensor.
  2. Examine the wiring for frayed wires or loose connections.
  3. Using a multimeter or ohmmeter, try out the sensor.

If you notice that your sensor is faulty, it means you have to change it. This is not difficult to carry out, but you should ensure that you are replacing it with the right sensor.

How To Reset the ABS Sensor?

  1. For you to reset your sensor, first, find the control module. Usually, you can find it beneath the hood close to your battery.
  2. As soon as you find the module, detach the battery’s negative cable.
  3. After doing this, press and hold down your brake pedal for about 30 seconds. It will let the system take out the residuals that might be inside the system.
  4. As soon as you have done this, you can now connect back the negative cable of the battery and start the car.

Also Read: How Long Does it Take to Replace Motor Mounts? (+ Cost)

Is It Safe to Drive when the ABS Light is On?

Is It Safe to Drive when the ABS Light is On

ABS symbolizes the anti-locking braking system. When your vehicle has the ABS feature, it means your car has an anti-locking braking system sensor. The function of this sensor is to keep an eye on the speed of the wheel and convey a sign to the controller whenever any of the wheels want to lock.

At this point, the controller activates your ABS pump, which releases brake liquid pressure to stop the locking of the wheel.

What Can a Faulty ABS Sensor Cause?

If any of the ABS sensors lag, it could result in a lot of problems. Certainly, the warning light would display on the dashboard to inform you that the system has a problem.

In addition, the vehicle’s braking power might be reduced, and in some situations, the system might not function, which can be dangerous. It is very necessary to be alert to these symptoms when they happen and take the vehicle to a mechanic immediately.

What Causes the ABS Sensor to Fail?

The reasons are few. One common reason is debris build-up, and dirt on your sensor can cause it. Gradually, the sensor will come to be less sensitive and, at a point, stop working.

Another reason is because of corrosion. The sensor tends to become corroded when you expose your vehicle to saltwater or any other corrosive substances.

The ABS sensor can go bad in some situations due to physical damage. The sensor might not function well if you have been in any type of event where the sensors get damaged.

Also Read: Transmission Speed Sensor Location

Bad ABS Sensor Symptoms

1. Illuminated Warning Lights

The dashboard has various lights that bring to your notice any danger. The ABS warning light is the first sign that will notify you whenever the anti-locking braking wheel speed sensor fails to work.

It might just trigger the ABS light at first. Nevertheless, when the supplementary part of the system stops working too, you may see the stability and control light too.

In rare situations, a bad wheel speed sensor would stop the speedometer from registering.

2. Thumping or Pulsating Brake Pedal While Braking

ABS sensor takes measurements of each wheel’s speed, so if any of the sensors go bad, it will read an incorrect speed for that wheel or any other one. This will trick the control module into feeling like the vehicle is skidding on slippery ground.

And this will kick in the traction control and the ABS. You will notice it by feeling a pumping or pulsating brake pedal when you brake.

3. Loss of Anti-lock Brakes

If the ABS wheel sensor becomes defective, it is difficult to operate the anti-lock brakes. If the system notices a fault, it alerts you by turning on the anti-lock brake warning light.

After the light turns on, the ECM of your vehicle stops getting essential data from your sensor. And the system depends on this data to know if the wheels are locking and need support.

The ABS stops working until you fix it because the system is not getting data.

4. Loss of Stability or Traction Control

Apart from losing anti-lock brakes, you can lose other functions, too, like the hill-start assist, roll stability, stability control, and traction control. The system and the computer close down when your sensor stops giving out data.

Nevertheless, you can encounter issues even if the ABS warning light is off. If you observe you are struggling in handling whenever you brake quickly, or you find it hard to keep control of the traction in bad weather conditions, the problem might be from the ABS wheel speed sensor.

This can be induced by a bad wiring connection that runs through the ECM and the sensor.

How to Tell Which ABS Sensor Is Bad

ABS Sensor Replacement Cost

To replace the ABS wheel speed sensor would cost around $200 to $400 for each sensor, based on the labor cost and the model of your car. That is to say, the wheel speed sensor would be around $209-$150 while labor costs $100-$300.

Most times, the wheel speed sensor for luxury cars tends to be more expensive; in addition, the model of your car might also increase the cost of labor as some of these models are more difficult to repair.

Replacing the ABS wheel speed sensor yourself is not that difficult using the right tools. You can do this in your garage if you have the fundamental knowledge. Though, it can get stuck for some time, so you can use heat to take it out.

Frequently Asked Questions – How to Tell Which ABS Sensor Is Bad

What happens when the ABS speed sensor goes bad?

When driving on icy or wet roads, and you come across a loss of traction or any kind of tire slippery for some time when taking off or stopping, this might cause the ABS not to function well. Usually, there’s an issue related to the sensor or the module.

How many ABS sensors does a car have?

It’s based on the kind of braking system a car has. A car might have just one or more than one sensors. The sensor normally has a magnet surrounding a coil and a tooth ring.

Can you clean ABS sensors?

If you can access the sensor, Use a rag to clean the sensor. You can avoid the use of chemicals to prevent trouble. Nevertheless, if the sensor is very grungy, make use of a light soapy mixture and rinse properly. In crude surroundings, ABS sensors are precision materials.

Can you drive with a bad ABS sensor?

In general, driving with a damaged wheel speed sensor is not safe. If the sensor wears out or gets damaged, at first, you might not notice it even if the light Is on. You can notice the difference when driving on a slippery surface.

Can a bad ABS sensor cause vibration?

A Faulty ABS sensor can cause vibrations until you service your car for replacement. In general, when your brake pedal is soft, it might signify that there’s an issue with the wheel speed sensor or the ABS sensor, though the system is separate.

Conclusion – How to Tell Which ABS Sensor Is Bad

You can make use of diagnostics equipment to inspect for faulty codes to tell which ABS sensor is bad, or you can scan the sensors visually.

If the ABS light comes on, you must have the vehicle inspected immediately, as driving with a bad ABS can be risky. You can wipe the sensor till it’s clean, or better still, go for replacement.

Scott Greene is a seasoned automotive technician for over 5 years and has been deep into advanced automotive diagnostics for a couple of years. He Loves writing about Automotive Diagnostics and Repair, Trouble codes, Buyer guides for various car parts and accessories, and lots more. 

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