If your car has a door ajar warning light, it's important to know what to do if it stays on. This light is usually located on the dash and indicates that one of the doors is not fully closed. If this light comes on, you should check all of the doors to make sure they are shut properly. If the light remains on after all of the doors are shut, it could be an indication of a problem with the door latch or another issue. In this case, it's best to take your car to a mechanic to have it checked out.