How To Tell Which ABS Sensor Is Bad

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You’ve been reading about ABS sensors, how they can get faulty, and cause your car to malfunction in several ways. But the common question in the minds of many drivers is how to tell which ABS sensor is bad. The number of ABS sensors in a car is dependent on the number of wheels.

ABS sensors are also referred to as wheel speed sensors because they are placed in strategic positions within the wheels’ hub to monitor speed and rotation.

When one of the sensors is bad, it can lead to other problems, and that’s the reason why you should learn how to detect a bad ABS sensor.

How To Tell Which ABS Sensor Is Bad

Mere dismantling your wheel hub to have a clear glimpse of the ABS sensor won’t prove to you whether it is bad or not. However, if the ABS sensor is physically damaged, such injury can be detected in this manner.

In contrast, when the ABS sensor is not physically damaged, you’ll need a technical, troubleshooting device to run diagnostic tests to determine if the sensor is actually the faulty one. For this troubleshooting to tell which ABS sensor is bad, we’d recommend that you use the .

 is a comprehensive OBD2 scanner with a lot of features. It can help you to detect the particular ABS sensor(s) that is constituting unusual problems on your car. So, using this OBD2 scan tool, you can get the answer you seek.

How to carry out the test:

detecting a bad abs sensor

  • Connect Autel MaxiCOM MK808 (or any other auto diagnosis tool that supports ABS scanning) to your car.
  • Boot the scanner and follow the instructions in the manual to make the scanner detect your vehicle. For Autel MaxiCOM MK808, click on the “Auto Detect” button at the top left. This will allow the scanner to autodetect your car’s VIN, and then you can proceed.
  • Once the scan tool is able to decode your car’s VIN and connects to your car’s computer, click on the “Control Unit.”
  • On the next page, tap on “ABS” to load the information about your vehicle’s anti-lock brake system.
  • Now, click on “Read Codes.” This will trigger a scanning interface – you’ll have to wait for some seconds/minutes.
  • After the scan is complete, Autel MaxiCOM MK808 (or your scan tool) would display the error codes retrieved from your vehicle. From here, you can spot the faulty wheel speed sensor(s).
  • However, to be more precise and get the exact result you seek, return to the previous interface where you clicked on “Read Codes.” But this time, you should click on “Live Data.”
  • The “Live Data” option will display real-time information regarding several components that make up the Anti-lock Braking System (ABS).
  • Scroll down and look out for the entries about “Wheel Speed Sensors.” By now, you should know that Wheel Speed Sensors are the same as ABS sensors.
  • Since the car is not moving, the wheel speed sensor should read “Zero” (0). Any of the wheel speed sensors that reads a number below or above “Zero” when the car is not moving is the culprit.

From the screenshot above, the faulty/bad ABS sensor is the one located in the “Left rear wheel hub.” It reads 255 even though the car is at a standstill. The “Live Data” results are arranged in alphabetical order; hence, the “Left Rear” and “Left Front” wheels data appeared first.

If you keep scrolling down, you will find the reading for the “Right Front” and “Right Rear” wheel speed sensors. They are also at “Zero,” which clearly indicates that the left rear ABS sensor is the bad one. Also, there is much other information displayed on the “Live Data” interface.

Diagnosing ABS Sensor Fault

How To Tell Which ABS Sensor Is Bad

Yes. If you use another OBD2 scan tool for this troubleshooting, the steps may differ, but you’ll yet get the same result/reading.

Furthermore, there are many other things you could do with an automobile scan tool. This includes scanning and fixing error codes, removing the check engine light on your dashboard, and more.

However, ensure to go through the user manual of any scan tool you decide to use for this test. Usually, OBD2 scan tools are connected to a car from the driver compartment. Then again, when you troubleshoot the ABS sensors and discover that they are all good, then you weren’t facing an ABS-related issue.

In such a situation, simply run a full diagnosis on your car using the OBD2 scan tool you already purchased. Ensure that the car is not moving when running this diagnosis.

Incorrect wiring can also cause the anti-lock braking system (ABS) to malfunction. Hence, the ABS wiring should be among your consideration when troubleshooting the problem you’re facing in your car. If all these seem complicated, kindly reach out to a mechanic.

Read Also: What Can a Faulty ABS Sensor Cause?


With the detailed steps above, we believe that our readers now know how to tell which ABS sensor is bad. Although we used the Autel MaxiCOM MK808, every other OBD2 scan tool out there support “Live Data” analysis, and that’s apparently the most effective way to spot a faulty ABS sensor regardless of the car.

In conclusion, when you discover the faulty ABS sensor(s), drive the car to a mechanic workshop and have an auto technician replace them. You may choose to replace the entire ABS sensors or just the faulty one(s). Driving with a bad ABS sensor can be dangerous – you may end up being faced with more expensive repairs.

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