Motion Sensor

@clarksoong2000  There are times in the past 8 years we experienced some "unexplained" happenings and then finally came up with the answer.  (My favorite was the motion sensor that appeared to "randomly" go off when we were shutting off the alarm. Spoiler alert: it was set on high and picked us up occasionally while we were opening the kitchen door to disarm the system via the keypad. Sometimes the motion signal was to the base before the door sensor.  Putting the sensitivity to medium did the trick.

For this one, besides the usual suspects (pet, air vent, sunlight -- did you cut down a tree -don't laugh a friend in TN did and the sun came in hitting the motion.  A small move and no more false alarms --- weak battery, possibly the fall invasion of stink bugs? Of course don't know your setup, house etc, but if you know someone who also has SS and can walk through the area and make some suggestions, you can also call SS support and discuss.  My kitchen scenario above was solved by a support rep on the 3rd call. Sounds easy now but hindsight is 20/20.

Good luck.