This repair guide will help you change the Mercedes wheel ABS speed sensor on models such as E, C, S, SL, CLS, ML, R, GL models.
If the wheel speed sensor fails on your Mercedes-Benz you will get ABS warning light on the dashboard plus your vehicle will go into LIMP mode and the transmission may no longer shift properly.
- ABS ESP Warning Light ON
- Fault codes such as Wheel speed sensor signal implausible or wheel speed sensor supply.
- Loss of anti-lock brakes.
- Electronic Stability Control (ESP) will be disabled.
- Erratic shifting of the transmission or limp mode in some cases.
A defective ABS sensor will illuminate the ABS, ETS, or ESP light on your instrument cluster. In rare cases, it may even set a check engine light or cause your car to not shift and go into limp (safe) mode.
With a bad wheel ABS sensor, the anti-lock brakes will not function properly and you increase the risk of skidding if you have emergency stops.
Some Mercedes-Benz haven an Allen bolt while others use a Torx bolt.
First, loosen the lug nuts but do not remove them. Second, raise the car using your jack. Third, support your car with jack stands such as Torin 3 Ton Jack Stands.
Locate Mercedes Wheel ABS Sensor
Remove the front wheel and locate the ABS wheel speed sensor.
Right behind the rotor, you will see a couple of cables connected to two sensors. One wire goes to the brake pads which is the brake pad wear sensor. The second sensor goes to the ABS wheel sensor.
Remove ABS sensor bolt
Use a Torx socket to remove the bolt that holds the ABS sensor in place.
The ABS sensor is held in place with a hex bolt which will require a 10mm Allen wrench to be removed. This is the ABS sensor, (also sometimes called RPM sensor) is located on the back of the steering knuckle.
Remove damaged ABS sensor
Pull out the old sensor.
It is a good idea to take a picture of the way that your ABS wire is routed. When you install the new sensor you may be wondering how and where to place the wire.
The ABS electrical wire is held in place by plastic clips. Pull the wiring harness away from the clips. You may have a plastic cover over the ABS sensor. Make sure to remove that before you pull out the ABS sensor. The plastic is typically held in place with clips that can be easily removed.
Disconnect ABS Sensor
Follow the ABS sensor cable to where it joins the connector under the front subframe.
Pull up the metal C clip and unplug the old sensor from the connector. To get to the connector you may have to remove the wheel well liner.
Separate the two connectors. You will need a small screwdriver to pry out the clips and separate the ABS and brake pad wear sensor.
Install new wheel ABS Sensor
Install the new Mercedes ABS sensor in reverse order. The ABS sensor bolt needs to be tightened to 25 Nm using a torque wrench. If you need to buy a new ABS sensor check out Amazon where you can order a new ABS sensor for under $50.
At the dealer, it cost between $400-$600 to change the ABS wheel speed sensor on Mercedes-Benz vehicles.
A new Mercedes-Benz wheel speed sensor can be purchased online, typically for under $100 and takes less than one hour to replace.
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