The intention of this thread is to describe my experience with an intermittent no-start/hesitant start issue that developed on my truck. In no way can I guarantee that the issue for me will be the same as your issue.

A few months prior to writing this thread, I had my original PATS key break (fatigue) while my truck and I were a few hours away from home. Since I didn't have a working spare with me, I had to call a locksmith who came out and cut and programmed two new Securilock (PATS) keys from Strattec Security Corp for a decent amount of $$$ (ouch). A few weeks later my truck started having an intermittent issue where it would hesitate to start (turn the key and after 2 or 3 seconds of nothing, it would start) or every once in awhile it wouldn't start at all and the theft light would start to flash.

I was able to gather enough patience to wait for the theft light to start flashing the code, and it was Code 13 (B1600) which basically means the PATS module was not able to read/recognize the key. I decided to swap in another transceiver (the part that goes around the lock cylinder and "picks up" the info from the chip in the key and sends it to the PATS module), but the replacement transceiver did the same thing. I was baffled, and in a last ditch effort I decided to try the second key that they had cut for me to see if there was a difference.

With the second key, the truck started right up. I repeated the test about five times over two days, and the second key always started the truck immediately upon turning it. I also was using the the first key in between my attempts with the second key, and each time I used the first key, the truck would hesitate to start. For the last week I have been using the second key, and the truck has started right up without issue. So it's clear that I have a bad chip in the first key and I have called the locksmith and set up an appointment for them to put a new chip in the first key. They were surprised when I described the issue as they have not heard of this happening often, and neither have I although anything is possible. Although the key somewhat works, I paid for a key that works as intended, not how it wants. Haha.

So if you're having issues with PATS code 13 or B1600, try a second key first, even if they're brand new like mine.

 

I have read of older keys doing that, but not brand new keys

PATS uses RFID(radio frequency identification) tags

RFID tag in a key handle would look like this: https://static.wikia.nocookie.net/it...20100914063122
Basically an antenna coil with a small chip that can hold a "number"
It is "powered" by the coil antenna getting a radio frequency "burst", and after that it does it's own "burst" of the number in the chip
When you turn on the key, the Transceiver fires a "burst", then gets the "burst", with the number, back from the RFID tag in the key's handle, but just to be clear, the transceiver is just an antenna, the PATS fires the "burst" with key on thru the transceiver, and PATS receives the number "burst" from the key from the transceiver

Now when making these RFID tags the coil antenna loop needs to be complete, no breaks, or there won't be enough power to send out the compete number, and of course the chip also needs to be in perfect working order with a complete number
They do make literally MILLIONS of these key tags, not just Ford that uses them, and Ford embeds them in MILLIONS of their keys
So I guess there would be a few 'stinkers' showing up along the way

 

I would have expected this from a cheap fake key off of Ebay or Amazon, but Strattec is one of Ford's approved suppliers for replacement keys with the 80 bit technology in my key (SA). But as you said, with millions in production, there's bound to be at least a few flukes. I'm just lucky enough to have ended up with one. Haha.

 

Well lucky enough to have it warrantied, lol

 

So to update this, I am now having issues with the second Strattec key. It was fine for a few months, and now it has started to fail as well. When I had the locksmith come back out to warranty the first key, he informed me that years ago they had a run of bad chips in the Strattec keys but he figured they were all gone by now. Apparently not. Haha. He ended up cutting me a key from a different manufacturer so when the Strattec key completely fails like the first (right now it's occasional), I will switch to the third key and hopefully that will be the end of this. I do have a spare original Ford key that I found after the first locksmith call, so I do have that to fall back on as well.

 

Thanks for the update