I just went through this whole issue witha locksmith.....The ignition cylinder (the keys slides into) are infamous for having the two wires break or rub and start to short out....The security system wont let the car start unless it gets a proper reading from the key and the igntion cylinder. Alot of people have to change the cylinder out.....Its $85 at the dealer..and I would go with delaer cuz the code is on th eoutisde compared to the mexico made aftermarkets and will cost you more money down the road if you lose a key. The locksmith also told me a trick to save alot of money is just soder or rewire new wires out of the cylinder and youll be fine..Its not easy though as youll have to take the steering column apart and need a steering wheel puller...(Autozone)......also if you no longer want the security feature..or no problems with yours now and dont want it anymore......start the car up and let it run about 5 mins and cut the orange lead wire that comes down from the column under your dash while the car is running...and then let it run another five min...and your car will always start without the securtiy feature ever again...but the light will stay on.....