Customer FAQs Discover answers to the most frequently asked questions from ADT customers with the click of a button. 1. What should I do if a door or window sensor falls off? If a door or window sensor becomes dislodged you can set the system to bypass the zone in which that contact is located, allowing you to keep the system armed with only those zones bypassed. For instructions on how to bypass a zone, you will need to refer to your system manual. If you do not have your system manual available, you can download one from our security systems user’s manual page.