Thanks for the info everyone.

 

Yes, but get the second key at the dealer and not a cloned key from a locksmith, since it (cloned key) emulates the first key and you cannot add a third key on your own since the car would see you trying to present the "same" key twice.

 

Hey guys, just joined, pretty cool forum. I got a 2006 Mustang V6 convertible. I too only got one key when I bought the car used. Lately the key seems to only work sometimes. Seems completely random as to when it may or may not work. I can usually get it to work by disconnecting the battery for 10 sec with headlights on to reset the computer but it getting annoying for my wife and kid to have to do this every time they go somewhere and it acts up. Also right around the time this started happening the new keyless remotes I bought and programmed stopped working. I have tried reprogramming them but that doesn't help. Wondering if the PATSII software could be corrupt or something. Anyone know how to fix this issue? I'm broke so I am trying to do it myself. Thanks for any help

 

Why don't you have the new key, it will be easily available at cheap from any locksmith near to your place.