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Trouble Condition: "Open"
If your door or window Sensor reads “Open” when it is actually closed, you may have installed the sensor improperly. Start by checking that the Bracket and Magnet are no more than ¾ inch apart. If they are, go back and repeat Sensor setup steps. Make sure Sensor placement is correct.

You can also check to see if Sensor extension is set by following these steps:
1.  Press MENU and scroll to Security Set Up
2.  Enter Master Code*
2.  Scroll to Sensors and press OK
3.  Select Sensor you are checking and press SENSOR EXTENSION
4.  Select Sensor Only (open/close door assign)
*Master Code is found on inside cover of the Quick Setup Guide.