wipe out old nissan remotes, after theft

My assumption is . . .

If the vehicle has more than one remote controller, the oldest ID code is erased when programming a new remote when there are already 4 ID codes in memory.

If there are less than 4 ID codes stored in memory, then the new ID code is added and no ID codes are erased, unless a new remote is programmed after filling all 4 memory positions. A maximum of 4 remotes can be programmed.

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Prepare your future. It wasn't the lack of stones that killed the stone age.

About the remotes, I don't know.

About the keys, though, I do know.

If you have the dealer (or a locksmith) re-program all the keys you have, any keys that are not present (as in the key the thief has) will be kicked out.

Of course, though, that key will still open the door

All these newer cars have all the transponders and crap, it gaets annoying. Since his car is an 06, he may consider doing what my wife's geandmother did when she was in the same EXACT situation. She had an 06 corolla and had her 2nd set of keys in hey ashtray(why, I dont know) but after having her car detailed a few days earlier, she came outside to find it paked a few feet back from where it is normally parked, the windows were rolled down and the seat was pushed all the way back(as if a tall person had been driving) and the car wreaked of marijuana smoke. She then noticed her keys missing. So apparently somebody stole it, went joyriding and then returned it. We thing its somebody who lives closeby since they returned it. After pricing what it would cost at the the dealer to rekey all the locks, reprogram the transponders, and the keyless remotes, they wanted well over 700 bucks. She then decided to just trade the car in for another one and her note only went up about 4 dollars.     
So depending on what all your friend has done to his car already and how many miles he has on it already, trading it in might be a good option. Then he will have a clean slate to work with.

All these newer cars have all the transponders and crap, it gets annoying. Since his car is an 06, he may consider doing what my wife's grandmother did when she was in the same EXACT situation. She had an 06 corolla and had her 2nd set of keys was in her ashtray(why, I dont know) but after having her car detailed a few days earlier, she came outside to find it paked a few feet back from where it is normally parked, the windows were rolled down and the seat was pushed all the way back(as if a tall person had been driving) and the car wreaked of marijuana smoke. She then noticed her keys missing from the ashtray(BINGO!) So apparently somebody stole it, went joyriding and then returned it. We thinK its somebody who lives closeby since they returned it. After pricing what it would cost at the the dealer to rekey all the locks, reprogram the transponder keys , and the keyless remotes, they wanted well over $700 bucks. She then decided to just trade the car in for another one and her note only went up about 4 dollars. She got several more options on the new car also.     
So depending on what all your friend has done to his car already and how many miles he has on it already, trading it in might be a good option. Then he will have a clean slate to work with.

that odd if they dont know if it will wipe out or not, take it to them and see if they can find out program new one then program anotehr multi times see if th eonter oen still can unlock the doors and such.