4matic sensor?
only pic I could find,autohausaz.com can quote them cheaper.

a crash course on your system can be found under 4matic wiki in google
When wheelspin is detected, the 4matic system operates two clutches in the transfer case in three stages using electro hydraulic valves located under your car.
There is a planetary gearset and two clutch packs inside the transfer case, and by locking one clutch and releasing the other your car is changed from being rear wheel driven into permanent four wheel driven during the first stage.
At the second stage, if wheelspin is still detected, the later clutch is released again and the transfer case is locked.
At the third stage, if wheelspin is still detected, the rear differential is locked by means of the third electro hydraulic valve.
You can see pictures of the speed senders in the attached photo, although I don´t think they´re causing your problems, the occasionally blinking light. Sounds more like the pressure sensor located in the electro hydraulic valve set located under your car. - Seen it happen on several occasions..

Cheers,



