SONOFF SNZB-02D Setup Guide: Pair, Place, and Calibrate the Zigbee LCD Sensor

Pair a SONOFF SNZB-02D temperature and humidity sensor with UpaSmartHome, choose where to mount it, fix a wrong reading, and troubleshoot pairing problems.

The SONOFF SNZB-02D is a small Zigbee temperature and humidity sensor with a built-in LCD, and it is the sensor that ships in the UpaSmartHome Starter Kit (five per kit, one per room). This guide covers pairing it, placing it well, correcting its readings, and what to do when it will not join.

What you need

A UpaSmartHome controller with a Zigbee coordinator already running (see our Zigbee vs Wi-Fi guide if you are still choosing hardware).
The UpaSmartHome app on iOS or Android.
The SNZB-02D with its battery tab pulled or a fresh battery fitted (it takes a CR2450 coin cell).

Pairing step by step

Keep the sensor within a couple of metres of the coordinator or a mains-powered Zigbee device for the first pairing.
In the UpaSmartHome app, start pairing mode. It stays open for a limited time only.
On the sensor, press and hold the reset button until the Zigbee icon on the LCD starts flashing (about five seconds), then release.
The sensor appears in the app as a discovered device. Confirm it and give it a clear room name such as "Kitchen". That name is what you will see in schedules, charts and voice assistants.

Once paired, the icon stops flashing and the app starts showing live temperature and humidity.

Where to place it

Mount it at about chest height on an interior wall, away from windows and direct sun.
Keep it away from radiators, boilers, cookers and other heat sources, and away from cold outside walls, or it will report the wall rather than the room.
For heating control, put it where you actually sit, not in a hallway. Our heating automation guide explains how the readings drive your boiler relay.

Correcting a wrong reading

Cheap sensors can be off by a fraction of a degree. Compare the SNZB-02D against a trusted thermometer in the same room for a few hours, note the difference, and apply it as an offset in the device settings of the Zigbee2MQTT instance running on your Pi (the temperature and humidity calibration options). Change it only once you are sure the sensor has settled in its final position.

Troubleshooting

Will not appear in the app: make sure pairing mode is still open, move the sensor closer, and repeat the button press. If it still fails, remove the battery for ten seconds and try again.
Readings stop updating: replace the battery, then check that a mains-powered Zigbee device sits between the sensor and the coordinator if the sensor is far away.
Gaps in the chart: usually weak signal at the sensor location. Add a Zigbee plug or relay nearby to strengthen the mesh.

Next: add door, window and leak sensors the same way.