All doors are closed.
Why would the door ajar alarm sound when I go over a bump? on 2008 Mazda CX-9
Find out which door is causing problem. You probably have a switch out of adjustment. Sometimes if you build up the head of the switch by putting 3or4 layers of tape it will push in the switch enough to find out. Remember, do one switch at a time. Goodluck
door ajar switch is going bad in one of the doors