My 2008 CX-9 has had some battery issues lately, a drain that's gone through two batteries. I recently jumped it to get it moving (to get a new battery) and the alarm keeps going off. The engine is running, I can shift into all gears, everything works, but the alarm will sound (exterior lights flashing, horn honking) for about 30 seconds. It will stop for a little bit (less than 15 seconds or so) and then start going off again.

I don't have a key transmitter, just a plain old metal key with no buttons, and it's just the one key. It isn't immobilizing the engine or stopping the car from doing any other function, just alarming. Pressing the lock/unlock buttons on the door doesn't make a difference either.

My thoughts are: the security system needs to be reset, the alarm is going off in response to a low battery (I haven't replaced it with a new one yet), or there's something else making the anti theft go off.

Any help?

 

How long have you had just the plain key?

 

I've had the key the whole time I've had the car, about a year and a half now. I've never had another key.