How To Clean Abs Sensor Ring

The ABS wheel speed sensor monitors road wheel movement and sends an electronic signal to the ABS / DSC module. This signal is used to calculate road wheel speed to help with ABS braking and stability control features. BMW E90 models utilize a magneto resistive style sensor. When an ABS wheel speed sensor fails, the ABS/DSC module loses road wheel speed for the corresponding wheel and sets a fault code for ABS wheel speed signal. When a fault code is set, the ABS/DSC warning light will illuminate. You will have to scan the module and read the fault codes to determine which speed sensor is the problem. Keep in mind, other problems can illuminate the ABS/DSC warning light, be sure to scan and read fault codes before replacing parts.

In this tech article, I will go over how to replace the front and rear ABS wheel speed sensors on BMW E90 vehicles.

Lift axle of vehicle you are replacing ABS sensor on. See our tech article on jacking up your vehicle.

Check out our complete Technical Article Directory for guides to many other procedures.

Check out our Basic Maintenance section, which has all the parts you'll need to get your vehicle running its best, including filters, fluids, brakes, spark plugs, lighting, and more for your E90!

Front ABS sensor:
Figure 1	Working behind front strut (yellow arrow), open plastic door (green arrow) for ABS sensor electrical connector. Large Image \| Extra-Large Image
Figure 2	Pull ABS sensor electrical connector out of holder. Disconnect by pressing release tabs and pulling apart. (green arrow) Be careful, these connectors become brittle over time and can crack if squeezed too hard. Then remove sensor wiring harness from mount on strut by pulling out. Large Image \| Extra-Large Image
Figure 3	Working at steering knuckle, remove ABS sensor 5mm Allen fastener. (green arrow) Using a long Allen bit makes it easier to get to fastener. Large Image \| Extra-Large Image
Figure 4	Pull ABS sensor out of steering knuckle. Then remove wiring harness from holders. Large Image \| Extra-Large Image
Figure 5	If sensor does not slide out easily, lever out using a flathead screwdriver. Lever close to the sensor and wiggle it out slowly. Install new sensor with a thin coating of Molykote Longterm 2 or similar grease to ABS sensor and housing. Install fastener and tighten. Then route wiring harness as it was before and reconnect at housing. Large Image \| Extra-Large Image
Rear ABS sensor: Remove rear wheel on side you are replacing sensor.
Figure 6	Working at rear wheel bearing carrier, remove ABS sensor 5mm Allen fastener. (green arrow) Using a long Allen bit makes it easier to get to fastener. Large Image \| Extra-Large Image
Figure 7	Pull ABS sensor out of wheel bearing carrier. Large Image \| Extra-Large Image
Figure 8	If sensor does not slide out easily, lever out using a flathead screwdriver (green arrow). Lever close to the sensor and wiggle it out slowly. Large Image \| Extra-Large Image
Figure 9	Working in wheel well, remove 10mm plastic nut. (green arrow) Large Image \| Extra-Large Image
Figure 10	Working in wheel well, pull wheel well liner away from body to access wheel speed sensor electrical connector. Pull ABS sensor electrical connector out of holder. Disconnect by pressing release tabs and pulling apart. (green arrow) Be careful, these connectors become brittle over time and can crack if squeezed too hard. Then remove sensor wiring harness from mount on strut by pulling out. Install new sensor with a thin coating of Molykote Longterm 2 or similar grease to ABS sensor and housing. Install fastener and tighten. Then route wiring harness as it was before and reconnect at housing. Large Image \| Extra-Large Image