As of yesterday, my wife's key no longer starts our 2002 Hyundai Santa Fe. The key turns fine, all electrical accessories work, but the starter is never engaged. My key (an original) works fine. I have another spare key (also a copy, like my wife's) that acts the same as my wife's.

Battery, starter, solenoid and fuses have all been checked (before it was narrowed down to the key). Both my wife's key and the spare key are > 5 years old, and my wife's has been used near-daily without any issues until yesterday. Not believing it wasn't just some sort of fluke, I repeatedly tried her key and then mine for 15 or 20 times with the same results.

These don't appear to be one of those new-fangled smart keys that everyone seems to have issues with. My wife's and my spare key don't have a rubber head, and are just regular keys. The Santa Fe does have a factory anti-theft system, but we haven't used it in years (the key fobs ate batteries too fast for my tastes) and no longer even carry the fobs.

Easy answer would seem to be that her key is "worn down" somehow (visual inspection doesn't offer any clues) - but with the spare key not working, is it possibly something in the ignition switch or key cylinder? Any other possibilities?

  • Are those dealer spares, or like hardware store spares? Commented Feb 25, 2012 at 6:44
  • @PetroEkos - Garden variety hardware store. Commented Feb 25, 2012 at 22:07
  • I'm wondering if the ant-theft system could be acting up, and the keys are not really the issue. Commented Feb 25, 2012 at 23:09
  • My car does the same! I have 3 keys. 1 org. 2 spares. 1 spare works and 1 doesn't.
    – user3141
    Commented May 10, 2013 at 18:19
  • Just happened on my 96 Toyota RAV4 . Both jets are sealed units and whilst I've been using the same one for last 2 years, last week it just didn't fire engine up. It turned it over but that was it. Recovery took car to local garage who said ECU was spiked. Would likely cost £250. Tried to reset remote zapper and took spare key with me. Tried old key but no good. Spare key fired it up no problem. Happy days. Not sure what problelem is but just glad I did not fork out £250.
    – Dave
    Commented Jul 11, 2017 at 12:19

2 Answers 2


The keys don't necessarily need a rubber head to be 'smart keys', some embed a small resistor inside of them that isn't very noticeable. The fact that the cylinder turns at all means the grooves aren't too worn, etc. It either matches the lock wafers or it doesn't.

I would look online for a programming method for new keys. It's likely that the battery went dead or otherwise lost its key programming. Usually the instructions will be something like putting the good key to ON (but not starting it) and back to OFF 5x, then putting the new key in and starting it (last time I did this was for a remote starter in a Mercury Sable).


if the key can unlock a door, but cannot start the car (while another key can), it is most likely a security mechanism in the key and/or keyfob (real/original one). I have first (and second hand) experience of this happening in Honda Odyssey's (i think it was a 2002).

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