Hello, there is a relearn procedure that you can try on the car and if it works you will be all set. If it does not work, the system will need to be checked with a dealer type class 2 scan device to find the problem. A regular code reader will not work as they can only read the engine and transmission computers and the theft system works through the body control module, so the correct scanner is all that will work on this system. Follow the instructions to the letter or this will not work.
Turn key to start position but do not start car, release key to the run position. Wait about 10 minutes until the security light turns off. Then turn key off. Repeat the procedure 3 times and then when you turn the key off wait 10 seconds. Then start the car, that should do it.