Xiaomi’s temperature and humidity sensors are some of the most popular smart home devices, thanks to their precision, compact design and affordable price. However, even a simple device like this can raise questions when you first connect: why the Mi Home doesn’t see the sensor, how to sync it properly with the app, or why readings get lost in a few days. This article will help you understand everything from unpacking to fine-tuning notifications, including solving typical problems.
We will look at three main sensor models: LYWSD03MMC (display-on), LYWSDCGQ (without display, with a replaceable battery, and TH1 (The instructions are relevant for the firmware Mi Home 2026 and Mi Home Lite, and also take into account the features of work in Russia, Europe and China. If you have already tried to connect the sensor and encountered an error, skip the basic steps and go straight to the section “Prevalent Errors and Their Solutions».
1.Preparation for connection: what to check before starting
Before you start syncing the sensor with the application, make sure that all the prerequisites are met, which will save 90% of the typical problems.
- 📱 The latest Mi Home app is installed (check out Google Play or App Store).Older versions may not support newer sensor models.
- 🌍 The region of accounts.mi.com is the same as the region of the app. If you are registered in China and the app is configured in Russia, the sensor will not connect.
- 🔋 The battery is inserted correctly. LYWSDCGQ and TH1 polarity is indicated on the body, but LYWSD03MMC Contacts can be hidden by protective film.
- 📶 Bluetooth on your smartphone is on. Xiaomi sensors use Bluetooth Low Energy (BLE) for initial synchronization.
Pay special attention to your account region, and if you bought the sensor from a Chinese store (e.g. AliExpress) but use the European version of Mi Home, you may need to change your region in your account settings.
- Open Mi Home → Profile → Settings → Country / Region.
- Choose China (Mainland China).
- Restart the app.
⚠️ Attention: Once the region is changed, all previously connected Xiaomi devices may appear as “unavailable” and will have to be reconnected. If you have a large smart home ecosystem, create a second account specifically for Chinese devices.
Step-by-step: how to connect the sensor to the Mi Home
The connection process takes no more than 5 minutes, if you follow a clear algorithm, and we'll discuss a universal method that is suitable for all sensor models.
Step 1: Activation of the sensor
Remove the sensor from the package and remove the protective film from the battery compartment (if any). CR2032 (for LYWSD03MMC and LYWSDCGQ) or AAA (for TH1). After that:
- Nana LYWSD03MMC The display with current indicators will light up.
- Nana LYWSDCGQ and TH1 flashes a blue indicator (1 time in 3 seconds).
Step 2: Adding the device to Mi Home
Open the Mi Home app and do the following:
- Press + → Add the device.
- Select the Sensor category.
- Find your model in the list (e.g., Temperature and Humidity Sensor 2 for the LYWSD03MMC).
- Click Connect and wait for the search window to appear.
Step 3: Synchronization over Bluetooth
When the app asks you to bring the smartphone closer to the sensor (up to 10 cm), do one of the actions depending on the model:
| Sensor model | Synchronization action | Indication of successful connection |
|---|---|---|
| LYWSD03MMC | Press and hold the button on the back for 5 seconds until the indicator flashes. | The display will show --.-°C, then current data |
| LYWSDCGQ | Press the button on the body 1 time (the indicator blinks faster) | Blue LED flashes 2 times in a row |
| TH1 | Remove and insert the battery back (reboot) | Red indicator lights up for 2 seconds |
If the synchronization is successful, a new device with current temperature and humidity readings will appear in the app, and if not, go to the Common Errors section.
The latest update to Mi Home| has been installed
The battery is inserted with the correct polarity|
Bluetooth on your smartphone enabled |
The sensor is within a radius of 1 meter from the phone|
The Mi Home app is open on the device add screen-->
3. Common mistakes and their solutions
Even if the instructions are executed correctly, the sensor may not connect the first time, and we have collected typical errors and ways to fix them, based on user feedback and Xiaomi technical documentation.
Error 1: “I couldn’t find the device”
Causes and solutions:
- 🔄 Bluetooth conflict: Disconnect other gadgets (earphones, fitness bracelets) and try again.
- 📵 Weak signal. Move into the room without interference (concrete walls, metal structures).
- 🔋 Battery's dead. Try replacing the battery, even if it's new -- factory failure is possible.
- 🌐 Make sure that the region in Mi Home and accounts.mi.com are the same.
Error 2: Sensor is connected but does not display data
If the device appears in the list, but shows --.-°C or old values:
- ⏳ Waiting for synchronization. LYWSDCGQ It takes up to 10 minutes for the first data update.
- 🔄 Forced Update: Open the device card in Mi Home and pull the screen down for manual update.
- 📡 Xiaomi server problems. Check the status of services at status.mi.com.
⚠️ Attention: If the sensor LYWSD03MMC It shows knowingly incorrect values (for example, the humidity of 99% in a dry room), most likely, the leakproofness of the case is violated.
What if the sensor is connected, but fell off a day later?
4. Set up notifications and automation
Once successfully connected, the sensor can be integrated into smart home scenarios, such as automatically turning on the humidifier at low humidity or sending a notification if the temperature in the nursery exceeded 25.°C.
How to set up alerts
Open the sensor card in Mi Home and go to Settings → Notifications. You can set thresholds here:
- 🌡️ Temperature: Specify the range (e.g., from 18)°C to 24°C) When going beyond the limits will be a push notification.
- 💧 Humidity: recommended range of 40-60%, for children's rooms can be narrowed to 45-55%.
- 🔔 Alert frequency: Choose Once per hour or Every time you go outside.
Integration with other Xiaomi devices
The temperature and humidity sensor can be associated with:
- 🌬️ Air humidifier (e.g. Xiaomi Smartmi Air Humidifier): automatically switched on when humidity is below 40%.
- ❄️ Air conditioner (Xiaomi Mi Air Conditioner): maintains a set temperature.
- 💡 Smart lamp (Yeelight): flashes red at critical indicators.
To create automation:
- Go to Profile → Automation → Add.
- Choose If → Temperature/humidity sensor → specify a condition (for example, temperature) > 25°C).
- Press To and select an action (turn on the humidifier, send a notification, etc.).
💡
If you have multiple sensors in different rooms, give them clear names in Mi Home (e.g., Kitchen, Balcony) and make it easier to set up automation and read graphs.
5. Model comparison: which sensor to choose
Xiaomi has several models of temperature and humidity sensors that are designed, accurate and functional, and below is a comparison table to help you choose.
| Model | Display. | precision | Battery | Features | Price (2026) |
|---|---|---|---|---|---|
| LYWSD03MMC | Got it (e-ink) | ±0.3°C / ±3% humidity | CR2032 (up to 2 years) | Compiled with a magnet for fastening | ~1 500 ₽ |
| LYWSDCGQ | No. | ±0.5°C / ±5% humidity | CR2032 (up to 1 year) | The cheapest model, replaceable battery | ~800 ₽ |
| TH1 | No. | ±0.3°C / ±3% humidity | AAA (6 months) | External sensor on the wire (up to 1.5 m) | ~1 200 ₽ |
LYWSD03MMC — the best choice for living spaces due to the accuracy and convenient display, and LYWSDCGQ suitable for technical rooms (basement, garage), where there is no need for constant monitoring of readings.
Which model to choose for different tasks?
- 🏠 Apartment/house: LYWSD03MMC (accurate, screened) or TH1 (If you need an external sensor on the street).
- 🏭 Greenhouse/basement: LYWSDCGQ (cheap, replaceable battery).
- 👶 Children's room: only LYWSD03MMC (margin of error).
6. Alternative ways of connecting (without Mi Home)
If you don’t want to use the official Mi Home app, there are alternative options for integrating the sensor into the smart home ecosystem.
Method 1: Through Home Assistant
Home Assistant – an open platform for smart homes that supports sensors Xiaomi via Bluetooth LE. For connection:
- Install Home Assistant on a Raspberry Pi or other server.
- Add Xiaomi integration BLE via the Settings menu → Devices and services.
- Follow the instructions of the setup wizard (required) MAC-sensor).
Method 2: Aqara Home App
Xiaomi sensors are compatible with the Aqara ecosystem (a subsidiary of Xiaomi).
- Download the Aqara Home app.
- Add the device through + → Add the device → Xiaomi.
- Sync over Bluetooth (similar to Mi Home).
⚠️ Note: When connected via Aqara Home, the sensor will only appear in this app and not sync with Mi Home!
💡
If you’re using Apple’s HomeKit, connect the sensor through Home Assistant with the HomeKit Bridge plugin.This is the only way Xiaomi sensors can be integrated into Apple’s ecosystem.
7. Update of firmware and sensor calibration
Over time, the accuracy of the sensors may decrease, and newer versions of firmware may correct errors, so let's look at how to update the software and calibrate the readings.
How to update firmware
Updates for Xiaomi sensors are rare, but they can be checked manually:
- Open the device card in Mi Home.
- Go to Settings → Update firmware.
- If a new version is available, click Update.
Important: Do not move away from the sensor during the update – the process takes 2-5 minutes, and an interruption can lead to a failure.
Calibration of readings
If the sensor shows deliberately incorrect values (for example, humidity of 30% at real 50%), it can be calibrated:
- 📏 Place the sensor next to the professional hygrometer for 12 hours.
- ⚖️ Manual adjustment. In Mi Home, go to Settings → Sizing and correction (e.g, +5% for humidity).
- 🔄 Reset to factory settings. LYWSD03MMC: Hold the 10 seconds button until the indicator flashes twice.