I am working on this type of problem right now.  My sensor housing cracked and broke where the threads meet the hex on top.  The new sensor connector seems to have a simpler design than the one I took off and wont accept the old connector--doesn't fit.  My existing fits on one way and has a wire clip on each side to hold it.  The new sensor isn't set up for that.  It's a shame because the old one goes together with the connector so well.  Does anyone  have and idea where to get a new connector to "graft" on?
  If the new sensor would have been same as old one it would have been a 2 minute repair.

  Chris C
  90Mv

Paul Guzyk <paullist08@GUZYK.COM> wrote:
  It could also be the connector to the coolant level sensor in the
expansion tank. Those fail more often than the sensor itself.

I've seen many of these connectors with corroded contacts. Pull back
the rubber boot on the connector and check the contacts. Graft on a
new connector to your engine bay wiring harness if necessary.