My Expedition's passive anti-theft system failing at temps below 15 degrees F.

What is your question?

I have a well maintained 2009 Expedition XLT with 137K miles and a good battery. Recently in cold weather the PATS system refuses to sense the Ford key and it locks up. Sometimes I can get it to start by sitting in the vehicle, closing the door and using the remote start which causes the doors to lock and the engine to start. Then if I then put the key in the ignition, of course the engine stops, but sometimes it then lets me restart the engine successfully. Other times it doesn't and I have to wait for some time and try again. It seems to begin around 15 degrees F and gets worse the colder it gets. Once it warms up outside I have no problem. Any Ideas? Doug Ferguson Palmer, Alaska

What makes this problem better or worse?

Colder temps as explained in the comments.

How long has your 2009 Ford Expedition had this problem?

About 5 weeks