1. Blocked sensor
Insects or plants can block the sensor. Be sure to keep the area clear.
2. Heat-based sensor false positives
If placed near a heat source like a fireplace or air conditioner, these will give off false alerts.
3. Dead batteries
Use long-lasting batteries and check them routinely. No battery juice equals a worthless device.
4. False detection of movement
Anything that moves can set off the alarm. Try to keep the sensor clear of potential moving branches, plants, or in places frequented by birds and other animals.