IS MY ABS WHEEL SPEED SENSOR BAD? SYMPTOMS, SIGNS, AND TROUBLESHOOTING
                     IS MY ABS WHEEL SPEED SENSOR BAD? 
SYMPTOMS, SIGNS, AND TROUBLESHOOTING
Mark Sanford
Writer at Brake System
University(https://brakesystems.autopartsu.com/) 
providing advice, reviews and information on brake system 
components including replacement brake lines, 
replacement ABS sensors, replacement brake line kits.
Most modern vehicles come equipped with anti-lock brakes, which means 
that the car also has up to four ABS wheel speed sensors. These units are 
mounted inside the wheel well and constantly monitor the RPM of each 
wheel and coordinate the data with the vehicle’s electronic control unit to 
determine when added brake power should be applied to maintain 
control. The failure of the ABS sensor is one of the most common 
problems found on anti-lock brake systems.
COMMON INDICATIONS OF A BAD ABS SENSOR
• Warning Light or Message Displayed on Your Dash: The most common 
sign is the ABS light appears on your instrument panel when you start the 
engine. In higher-end models, your driver information center may display a 
maintenance message.
• Stopping Distance Increases: Does it seem like it is taking longer to slow 
your vehicle? Or you may notice your tires slipping and skidding on heavy 
deceleration.
• Loss of Control on Rough Roads and through Heavy Weather: When the 
ABS wheel speed sensor fails, your vehicle will also disable traction control, 
which reduces your ability to navigate icy conditions or work tight turns 
while maintaining good car control.
REPAIR OR REPLACE?
Just because you have an error light appearing for your ABS system, it does 
not mean that you have to replace all four sensors. First, determine which 
wheel sensor is causing the error by connecting to your OBD diagnostic 
reader. Before deciding to replace the sensor, you will want to take the 
time to check the wiring harness and wires to the sensor as these are the 
most common points of failure outside the actual sensor module.
• Put the car up on a jack and remove the tire to get good access to the 
area.
• Disconnect the car battery to prevent shorting out the ABS sensor during 
troubleshooting.
• Disconnect and reconnect the wheel speed sensor at the wire harness 
and reconnect the car battery.
• Clear error codes using your OBD reader
• Restart ignition and see if the ABS warning light returns.
If the warning light persists, you will need to replace the ABS sensor. The 
sensor is sold as a single unit with all wires connected, ready to plug and 
play.
DO-IT-YOURSELF TIPS
Changing out the sensor yourself is not that complicated. The unit is a 
small sensor that is bolted to the wheel-hub assembly and requires the 
appropriate socket wrench or screwdriver to remove and install it. Check 
your maintenance manual to properly identify its location and appearance. 
Before proceeding:
1. Disconnect your car battery to prevent damage to the new unit during 
connection.
2. Loosen the lugs on the wheel before you put it up on jacks or the lift.
3. Map out the path of the wire that runs from the wheel hub to the ECU 
connection under the hood. You may need some needle-nose pliers to 
loosen grommets and clips that keep the wire in place.
4. Have a flat tool ready that is able to help loosen the sensor from the 
wheel hub as road grime and corrosion can make it difficult to remove.
You can find a complete selection of ABS wheel speed sensors and brake 
repair supplies at Carlson Quality Brake Parts.
About Brake System U
Brake System University is a micro site giving advice, reviews, and technical 
information on various brake system components like brake lines, brake 
line kits, and ABS sensors. Brake System University connects you to high 
quality, genuine brake system replacement parts including  replacement 
brake lines, replacement ABS sensors, replacement brake line kits that 
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