JB weld is an epoxy.. Its strong as holy hell and has been used to "fix" such small cracks in engine blocks.
I had a cracked transmission housing in a pontiac that I actually JB welded back together and drove on for a couple of months before it failed catastrophically. I was impressed. Gave me time to save up and source another trans.
If I were to try that on this application, I would rough up the surface all the way around, clean the hell out of it, inside and out of the crack, mix up the JB weld, massage in into the crack, and all the way around the piece, then put a hose clamp around the whole thing, tighten it down, and apply JB weld over the entire clamp. Chase the threads to clean them up. That way you have a sealer and support so it doesn't crack again when you put the sensor back in.
This is ghetto as hell but it would probably work.
Do it right, take it to a machine shop! lol