I have just recently bought an "03 Tiburon GS and only have one keyless remote for now and I had the key in the ignition with the engine running and got out of the car to shut my garage door came back to get back in the car and the door locks locked automatically with the car running. Luckily I had the sunroof open to where I could get a broom handle and push the door lock mechanism open to gain access back in the car. Is this normal and supposed to do that? I thought the car would sense the key in the ignition and stay unlocked but I was mistaken. I guess I wont be doing that again.

 

My Tib is an 04 and I am able to keep it running and my doors will not lock on me. I assume it should be the same with your 03 model unless Hyundai didn't impliment that option until after your model was designed...??? Good luck on getting a more accurate answer.

 

Get one of those magnetic key hider things, put an extra key in it and hide it somewhere under the car. That way you're never locked out.

The cost of a duplicate key and the key finder is about $6 total. Cost for a locksmith is at least $25 and they may damage the door, seal or both to unlock it.

 

it shouldn't lock by itself. once key is in the ignition its suppose to lock. if it happens again probably you have a problem with the bcm. try it with the windows down and see if it happens