Yeah, the pairing process can be finicky. The trick is getting the sensor into its discovery mode at the right time.
First, press and hold the button on the wireless sensor itself for a solid 15 seconds. You'll know it's working when the LED on the sensor turns Amber. Keep holding until it does.
Now, immediately go to your thermostat. Press Menu, then go to Devices and Sensors. Follow the on-screen instructions to add a new sensor. The thermostat should find it.
If that didn't work: The main issue is usually range or interference. The sensor has up to a 200-foot range, but walls and other electronics can cut that down.
- Bring the sensor right next to the thermostat and try the pairing process again.
- Make sure you're not trying to connect more than 20 sensors—that's the limit.
- If it's an older sensor, the battery might be dead. It likely uses a standard coin cell.