It's gong to be very hard to clean the rear face of the wheel bearing without first removing the drive axle and then the bearing/hub assembly. And note that if you remove the bearing/hub assembly, you'll need new bearing retainer bolts - they are single-use.

You could try spraying a ton of WD40 into the hole where the speed sensor fits, while rotating the hub. That might flush most of the crap out... into a drain tray under the hub.

As for the sensor part, the older (superseded) part should still work - unless something else has been modified in the car (unlikely).

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Wayne
2005 BMW X5 3.0d (b 02/05)
2001 BMW F650GS Dakar (b 06/01)