Entry Sensor fails in cold room.
One of my entry sensors is in an unheated and un-air-conditioned room. It worked perfectly from March through October, but it began to send "sensor error" notices with each cold snap. It would send a "restored" notice each time it warmed up. I didn't relate it with cold weather at first, so I replaced it (had to buy a 4 pack). But the new one is following the same pattern. They do not work in a cold room.