Speed sensor


Cost: $50


The Speed sensor on the BMW E34 is located at the back of the differential housing in an inaccessible location... follow the only wire. You will find a lot of dirt and grease over there, so be prepared and wear protective glasses and gloves.

Failure syndromes:
• Erratic or no speedometer, erratic or no speed control, erratic wipers functioning.


Procedure Step by step procedure
  • Protective glasses
  • WD 40, the screws might be rusted
  • 3/8" Ratchet, extensions and u-joints
  • 10 mm socket and open wrench

1. Place the rear of the car on jacks or use a ramp, then spray the old sensor two screws with WD40. Now that you have found where the screws are... you know that removing them is going to be tricky.
If you are not a patient person, grab your phone and call the dealer...

2. After approximately 1 hour, you have removed the screws. Try to clean your sensor, it might work again (it didn't work for me). If cleaning it does not work, just change the sensor.
3. Tighten the screw with a 10mm open wrench then finish with the ratchet and extensions.

Best advice : Be patient...

Addition from: Bob K.
The hard part is getting to the bottom screw, IMO. Having a heckuva time getting it started after
removal, I decided to do the following:
. support the differential with a hydraulic jack
. remove the two bolts (19mm head) holding the rear of the diff to the suspension member
. drop the diff about an inch or less

The issue is ensuring that the diff is supported. What dropping the diff does is give enough room
to get a direct angle on the bolt, both for removal and replacement. A caveat is to do the removal
and replacement of the top bolt before and after the diff drop, respectively.

Also, I found that my 3/8" drive sockets were a tad thick for the available clearance. I used 1/4"
hardware with a 3/8" to 1/4" adaptor.

Regardless, it certainly is a job that requires patience.

Addition from Ivan C.
Thought you might want to know, I replaced my speed sensor and while it was time consuming, it was really not too difficult. Most of the time was de-greasing and cleaning area first.
I used 1/4" vs 3/8" tools: 10mm open wrench, 1/4" 10mm socket, 1/4" ratchet with 3" and 5" extensions and "u" joint. and had no problem reaching lower and upper bolts as follows:
Upper bolt: Socket drive to 5" extension to U joint to 3" extension with 10mm socket: between gas tank shield and suspension / diff
Lower bolt: Socket drive to 3" extension to U joint with 10mm socket: between suspension and diff

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