hi. i'm riding a '04 950 adv...i came across a similar problem. it started with the numbers on the speedo jumping here and there, not giving the correct speed. it ended with it not showing anything but a big "0". what i did was i sprayed the sensor with some aerosol degreaser, and hosed it off. it worked fine after that. i've been doing it ever since then, whenever the problem arises. it seems like a simple enough solution...too simple in fact. but it worked for me. i hope this helps.