This sensor failed at 84600 miles, and was replaced by the local Ford
dealer. The magnet had come loose from the top of the cam stator assy
and had damaged the synchronizer, requiring both to be replaced. The
synchronizer requires special tooling to install, which is why I chose
to have the local dealer do the repair.
At 96000 miles, the same failure occurred with the replacement parts -
magnet came loose again. It was within the 12 mo/12K mile warranty
period and was replaced free of charge by the dealer. (Otherwise it
would have cost $350 total)
My concern is that this may become an expected recurring failure with
this year vehicle. The replacement parts may be of a poor
design/quality. Not only is it expensive, but requires that the car
be taken in for repair and be out of service. Looking at the cam
stator assy under a microscope, it appears that the plastic stub
holding the magnet has disintegrated, causing it to drop the magnet
into the spinning synchronizer. If this is a plastics polymerization
problem with heat, then most all of these replacement cam stator assys
in Ford stock can be expected to start showing the same failures.
Fortunately the computer is smart enough to allow the engine to run
with the failure, so it does not need to be towed.
The replacement parts for each repair are of identical Ford stock
AA Cam Stator Assy (Hall Effect)
BA Synchronizer Assy - Eng Ctrl