Braking System

How To Tell Which ABS Sensor Is Bad?

Mike Cross
Updated Feb 8, 2022
How To Tell Which ABS Sensor Is Bad?

Your ABS system is a key system in your car. ABS stands for the anti-locking brake system, and it is what helps your breaks from locking up if stopping quickly.

If your car has an ABS light on, then that means the ABS will not work, and your wheels might lock up on you when trying to stop. That is why it is important to fix this problem as soon as possible.  When your abs light is on, you should use best bluetooth obd2 scanner to find your error code, check the list here

In this article, we will talk about how to tell which ABS sensor is bad so you can have it replaced and also what to do to prevent the ABS light from coming on again after replacing the sensor.


How To Tell Which ABS Sensor Is Bad?
How To Tell Which ABS Sensor Is Bad?

Where is ABS sensor in your Car?

Before you can test your ABS sensor, you first have to know where it is located. For all cars, it is in different spots, but it is normally located somewhere near the back of the wheel.

You can look at a diagram of your vehicle, but the ABS sensor will be a small sensor with a connector going to it behind the wheel hub.

When searching for the ABS sensor you want to make sure you don’t accidentally locate the brake pad wear sensor or other wiring harnesses. Once you have located the ABS sensor, it is time to test it to see if it is the one that is bad or not.

How to Test ABS Sensor

Testing the ABS sensor is easy, and it only takes a couple of steps to test each one. The first thing you need to do to test the ABS sensor is to get a voltmeter ready and then locate the ABS sensor with the method that we have mentioned.

Once you have located your first ABS sensor, you can disconnect the wires from it carefully. Then you can clamp the voltmeter probes to the connection on the ABS sensor. It is a good idea to use a voltmeter that has clamps because hand holding the probes on the ABS sensor can be challenging.

Once you have the voltmeter connected, you can turn it on and set it to AC or alternating current. It is important to make sure the probes aren’t touching or else it will mess up the reading.

Once the voltmeter is on it should drop down to a reading of zero. Once it is at zero volts, the system is ready to test.

How to Test ABS Sensor
How to Test ABS Sensor

To test the ABS sensor all you have to do is spin the wheel hub with your hand. It is important to do this slowly. Spinning the hub will cause a charge, and this will give the voltmeter reading. If the sensor is working right, the reading will be around 400 AC voltage. The reading will depend on how fast you spin the hub though and can vary based on the car.

After testing the sensor if you get a correct reading, then you can move on to the next sensor. If the reading is off though, then check behind the wheel for a gear with teeth called an ABS reluctor.

You will want to spin this and check to make sure all the teeth are there and not damaged. This can cause a bad reading, and it might not actually be the sensor. Also, wheel sensors are magnetic, so you will want to clear any metal shavings from this and then test the ABS sensor again. When you test the sensor again if it is still giving an off reading, then it is probably the bad one.

Tips to test ABS sensors

This video show you how to tell which ABS sensor is bad with obd2 scanner. Try to find one to do it.

When testing your cars ABS sensors to try to locate the bad one, it normally easies to jack the car up and put it on jack stands. This way you can take all four wheels off at once and test all the sensors right back to back.

That way you won’t have to keep raising and lowering the car down to test different sensors and deal with removing tires and putting them back on. If you can get all four wheels off the ground at once, then this will save you a lot of time when trying to find the bad ABS sensor.

After testing all four sensors if none read bad or if you clean around all the sensors and none read bad, then you should be good to go. However, if you put the tires back on and get an ABS light again, then you know that there still is an issue with the system. The issue is probably within the wiring of the ABS system and this can be harder to find but can be done with a voltmeter set to ohms to measure resistance.

Checking wires

To check the wires within the system, you will want to set the voltmeter to ohms and get a wiring diagram.

You will have to test each wire from end to end. To do this, you just connect the probe to each end of the wire and see that you are getting a reading.

If you are, then that wire is good.

If you don’t, then that wire is shorted or broken.

You will need to replace that wire. Once you have tested and replaced all the damaged wires, then this should fix the system, and the ABS light should go off, and the system should start working correctly again.


So, now you know how to test your ABS sensors to find out which one is bad. Using a voltmeter, you can connect it to the ABS sensor and turn the wheel to get a reading.

If you don’t or it is wrong, you can clean the ABS reluctor. If the reading is still incorrect, you know which sensor to replace. You also know though that sometimes the sensors may not be what is causing the ABS light and instead it is bad wiring.

You now know how to test this as well with a voltmeter set to ohms and a wiring diagram. You know how to find the bad wires that need to be replaced to fix the ABS system.

Checking ABS sensors isn’t too hard and finding which one to replace isn’t that hard either now that you know how. All you need to do is jack your car off and get the wheels off, and you will be able to diagnose and find which ABS sensor is bad and fix your ABS system in no time.

Mike Cross
Life is too short to drive with stock audio

Leave a Reply

Your email address will not be published. Required fields are marked *

One comment on “How To Tell Which ABS Sensor Is Bad?”

  1. I found the hard way that not all ABS sensors work the same way. Older ones use a coil and a magnet close to the reluctor (or tonewheel) which generates a small voltage (not 400V surely, more likely 400 mV) but later ones use the Hall effect, which requires a DC supply and some miniature electronics inside the sensor. I didn't think this could be done with only two wires, but my son who has an electrical engineering degree showed me how it could. A multimeter will test the old sort, but you would need to connect two wires to the sensor while it was working, and turn the wheel slowly, when the voltage should jump up and down many times as you turn the wheel one turn.

linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram