SEM Security Systems
a division of Southeast Mobility Inc
So, your yellow light is on, the keypad is beeping, you've pressed *2 and the keypad is displaying a 5, or it read out Zone Fault.

This indicates that the panel has lost communications with one of the contacts or sensors on the system. A zone fault is usually caused by either a low battery on a wireless contact or a problem with the wiring on a wired contact. Follow the instructions for replacing a low battery if the contact, or sensor, is wireless and you will probably solve the problem. If it is a wired contact then you may want to schedule a service call since this will usually involve a trip into the attic or crawl space. Zone faults on wired contacts are most often the result of a mouse feasting on the wiring.