Programing new key

[JamesBond]

So I picked up a used 06' Explorer and it only came with one key. I want to get another one so I have two keys.
But everything I've read about programing a new key says you have to already have two working keys. :scratch:
Why couldn't I just insert the one working key I have twice to program the new one?

 

[Kavlainc]

Also had the same situation. From what I've read online you have to get the second key programmed by the dealer if you only have one key. I was hesitent about trying to program myself, did not want to stall the engine.
Here's what I've done with the second key. Got a blank key from ebay for about $12.50. Took it to the local lowe's and they cut it for free. So that key could just open the door. No way around the last step, found the cheapest dealer who also gave me a 10% discount on programming, which came out to be around $47.50. So the second key was $60, not too bad. Another ford dealership wanted $100 ($40 to get cut and $60 to program) for a new key, so shop around.

 

[JamesBond]

I don't think there's any chance of stalling the engine, it just wouldn't program the new key.
But I'm still not seeing why the same key twice wouldn't work?

 

[jupiterak]

You need two keys to program a third key. Since you only have one key. Check out the local local locksmith. Some may have the programmer to do it and it'll be cheaper than the dealer. It only takes about 10 minutes to do it.

 

[DavidEBSmith]

Lots of info on the PATS system at this thread.

The simple answer to why the same key won't work twice is that each key has its own unique code. If the system is looking for 2 different keys to allow you to program the 3rd, it won't see 2 different keys if you use the same one twice.

As to why it looks for 2 different keys - if you could program a new key using only one already-programmed key, anybody who got access to that one key (say, a parking valet, or a mechanic at the shop) could make duplicate keys very easily. If somebody needs 2 already-programmed keys to program a new key, the odds of getting access to 2 physical keys at the same time are much less. Some early models would allow you to program new keys with only one programmed key but the risks apparently became obvious quickly.

According to the thread linked above, if all the key codes have been erased or if only one is programmed, you can program a new key with one already-programmed key, but you would only have fewer than 2 keys programmed if you had erased all the codes with the special tool at the Ford dealer (or maybe if you installed a new PATS module?) and if you had access to the special tool, you would presumably just use it to program the keys.