2003 Nissan Altima starting (security issue?)

About a week ago my Altima wouldn't start. Engine turned over fine. It just wouldn't fire up. Took it to a mechanic and he said it was a
security thing. i brought him a different key and the car worked fine (although i wasn't there to see what was done).
I took it home. Turned it off and started it again -- worked fine.
In the meantime, the wife used a different key and now it doesn't start again. It doesn't work with any key.
I get the feeling that he did something to it to reset some security setting; I just un-hooked the battery and will leave it sit for a couple hours, but if that doesn't work: does anyone have any ideas or experience with this security issue?? I had no idea my car had a computer chip in the key until this problem arose. email me at ioffer(nospam)@offthehookfineart.nospam.com
Thanks! Jeremy
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Hi My 2K Altima had intermittent problems not starting when I first got it and it appeared to be related to my Mobil speedpass key fob. The car would behave like it was flooded. Apparently, other fobs interfere with their RF ID security button integrated in the Altima's key. Under normal circumstances, it should not interfere beause RF ID is a very robust system, but I guess they did something wrong in their implementation of it.
If you have one of those speedpass fobs, remove it from your keyring and see if it gets better.
Remco
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Yeah, there's a security chip embedded in the key. the engine will not start if this key doesn't have the right coding. In the manual it says that it's possible for the security key to lose its memory and worse.. the car can lose its settings and then requires a dealership reset. nice security feature.
anyone know if there's a battery in the key or something? Can it go dead too?
Also, we're experiencing the same problems with our '02 altima.. runs fine the dies, starts up, dies.. No rhyme or reason..

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I've actually designed a system with these chips ("RF ID tags") in them, albeit not for cars. Allow me to bore you with some details: :)
The cheaper ones do not have batteries in them. They are activated by being in close proximiy to the transmitter (somewhere near your lock, I suspect) and get a small charge from the transmitter's RF field, just enough to burst a serial number to the transmitter. One can have tags with a preset serial number but some also contain data that is one time programmable from the factory. The more advanced ones are encrypted. On my Altima 2K it seems to just burst a string of binary data.
The more expensive tags have a battery in them and do have some memory. I find it hard to believe they'd use that inside a car because there really isn't much of a need to write any information to them. I've seen the dealer pair my key with my car by plugging a special tool in the diagnostics port and pressing a sequence on the tool while my new key was inserted. One would imagine the computer just takes note of the key's serial number as being legitimate. So most likely the programming lost is that of the car's computer.
I do know that my car had issues when another RF ID was placed next to the key. It being RF (and RF being absorbed easily by any metal in the viscinity), it could be that the other keys on they keychain interfere with the communications between the altima key and computer and one needs to use the key all by itself. Try it to see if that helps. Not sure why they put this tag on a key -- seems to me that's just another thing that can easily fail but maybe that is just what they want, huh?
Remco
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