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Pelican Technical Article:

ABS Sensor Replacement

Nick Czerula

Time:

2 hours2 hrs

Tab:

$50 to $70

Talent:

****

Tools:

Phillips & flat-head screwdriver, scan tool (to identify faulty sensor)

Applicable Models:

BMW E46 3-Series (1999-06)

Parts Required:

ABS wheel speed sensor, Molykote Longterm 2 grease

Hot Tip:

Be careful when removing, sensor can break off in vehicle

Performance Gain:

Repair faulty ABS sensor

Complementary Modification:

Properly route wiring, use new clips if needed

The ABS wheel speed sensor monitors road wheel rotation 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 E46 models were equipped with three different types of wheel speed sensor depending on the ABS system used in the vehicle

  • Inductive sensor used in TEVES MK 20 ASC / DSC (1999-2000 models)
  • Magnetoresistive sensor used in TEVES MK 60 DSC (2001-2005 models)
  • Hall effect sensor used in Bosch DSC III 5.7 (2001-2005 models)

The Hall-effect sensor and the magnetoresistive sensor for the rear wheel are physically interchangeable. They do the same job but are electrically different and cannot be interchanged. Be sure you are installing the correct sensor type when replacing. One way to tell which system is used in your vehicle is to inspect the space below the brake master cylinder in the left rear engine compartment. The Bosch system (Hall effect sensor) is equipped with a DSC pre-charge pump, a cylindrical unit installed just below the master cylinder. The TEVES system (magnetoresistive sensors) is not equipped with the pre-charge pump.

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 the ABS wheel speed signal. When a fault code is set, the ABS/DSC warning light illuminates. Although you do not need a scan tool to replace a speed sensor per se, you have to scan the module and read the fault codes to determine which speed sensor is the problem. Keep in mind that other problems can illuminate the ABS/DSC warning light, so be sure to scan and read fault codes before replacing parts.

Wheel speed sensors are bolted to each wheel hub and are therefore susceptible to damage from impacts, road grime and brake dust. In this tech article, I will go over how to replace the front and rear wheel speed sensors.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches. 

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you are working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability. 

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

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

Front ABS sensor:
Working behind front strut (purple arrow), open plastic door (green arrow) for ABS sensor electrical connector.
Figure 1

Working behind front strut (purple arrow), open plastic door (green arrow) for ABS sensor electrical connector.

Pull ABS sensor electrical connector out of holder.
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.

Working at steering knuckle, remove ABS sensor 5mm Allen fastener (green arrow).
Figure 3

Working at steering knuckle, remove ABS sensor 5mm Allen fastener (green arrow).

Pull ABS sensor out of steering knuckle.
Figure 4

Pull ABS sensor out of steering knuckle. Then remove wiring harness from holders. If sensor does not slide out easily, lever out using a flat-head 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.

Rear ABS sensor:
Remove rear wheel on side you are replacing sensor.
Figure 5

Remove rear wheel on side you are replacing sensor. Working in front of rear trailing arm, open plastic door (green arrow) for ABS sensor electrical connector. Then remove wiring harness from holders along trailing arm. Use a small flat-head screwdriver to open holders.

Working at rear wheel bearing carrier, remove ABS sensor 5mm Allen fastener (green arrow).
Figure 6

Working at rear wheel bearing carrier, remove ABS sensor 5mm Allen fastener (green arrow).

Pull ABS sensor out of wheel bearing carrier.
Figure 7

Pull ABS sensor out of wheel bearing carrier. If sensor does not slide out easily, lever out using a flat-head screwdriver. Lever close to the sensor and wiggle it out slowly.


Install the 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.

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Comments and Suggestions:
Jim Comments: Can you price me for all 4 wheel speed abs sensors. Wbaav33421ee77135. 2001 bmw325i built 01/2001.
August 10, 2016
  Followup from the Pelican Staff: See this page:

http://www.pelicanparts.com/cgi-bin/supertech/catalog.cgi?action=frameset&return-url=/cgi-bin/supertech/catalog.cgi%3Faction%3Dframeback%26page%3D1109&catalog-url=http%3A%2F%2Fwww.pelicanparts.com%2Fcatalog%2FSuperCat%2F0216%2FBMW_0216_BRKHYD_pg5.htm %3Futm_source%3DSuperTech%23item18

Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Denis Comments: I just need a wheel speed sensor, 3 WIRE, Hall Effect. It can be off of any BMW, doesn't matter. It is not an OEM replacement for me but for something aftermarket I am doing.
April 7, 2016
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can can get you one.
- Nick at Pelican Parts
 
Denis Comments: Can you give me a part number for E46 HALL EFFECT FRONT Sensor? I can't find it anywhere!
April 6, 2016
  Followup from the Pelican Staff: For a wheel speed sensor? We would need to know the year and model. For a faster response, Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Sundance Comments: I have a 2003 325i the speedometer is out the ABS, Brake and DSC light are all on, I was told that it was most likely the driver side rear speed sensor. so I bought one here and installed it last week. Still no speedometer and all the warning light are on. Any ideas
October 3, 2015
  Followup from the Pelican Staff: Could be the wiring or the module. Start by checking the vehicle for fault codes. - Nick at Pelican Parts  
Esa2020 Comments: Now my problem is that its only flashing intermittently when i start the car, what could be wrong here?
Thanks in advance.
October 2, 2015
  Followup from the Pelican Staff: What is flashing? - Nick at Pelican Parts  

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Page last updated: Wed 12/7/2016 02:21:21 AM