2007 Key Fob SKS New Housing or cover

Have you ruled out the keyfob battery? I didn't read all the posts, just thought you might try another new battery from a different vendor

SM-N900P ?

 

The battery is good enough to flash the red LED on the keyfob. I've noticed that the keyfob still works for a while after the LED dims out.

But here's another test: watch the keyfob LED as you approach the car. If the proximity function is working, the LED will flash at about 3 feet from the antenna in the door. If you have a radio that can tune to 134.5 Khz (or double that at 269 Khz), you can hear the car polling for a keyfob. When the keyfob comes in range (about 3 feet), the chatter on the radio gets a lot more excited.

 

It's another diagnostic that will narrow down what the failure is. Think of detecting the car poll as pressing an unseen button on the keyfob.

My guess is that the security ECU on the car lost registration of the keyfob. Reregistering the keyfob will probably work. So if there were another functional keyfob, the problem one would register with the simple "add keyfob" function - no seed required.

But there's only one keyfob, and it doesn't work. So I'd get another one functioning before trying to reregister the old one. Either way, it's going to require a seed reset. May as well use the seed to enable registering a keyfob that should work (used or new, no practical difference here except for the price).

 

You just have to reseed with the keyfob you currently have. If you don't have a spare fob now, you can get the spare programmed (you can programmed a used fob) the same time when you reseed.

 

Unless you have equipment to test the motherboard, you won't know if it's the motherboard or simply the car has lost it's programming to the keyfob. Your best solution now is to get a reseed to reset all the keys and start over.

1. buy a used/new keyfob for reseeding
2. reseed the car and get that keyfob working.
3. try to program the possibly damaged keyfob at the same time.

If the "damaged" keyfob works, it'll get programmed and you'll have a 2nd fob. If it's damaged, just throw it away. If you have a properly working keyfob, you can self program a new keyfob