A couple of days ago my engine just stopped while on cruise at highway
speed. The engine had been running quite happily for about an hour.

The only light on the dashboard that lighted was the green immobilizer
light which is the reason I look in that direction. I turned off the
ignition and restarted the car immediately with no problem. The
problem has only occurred once, so far.

My concern is that this may be the start of some issues with the
immobilizer. I am guessing that either the immobilizer receiver or
the control module is failing. Is there any way to find the problem
before it fails completely and leaves me on the road with an immobile
car?

Thanks.