The Nuki app will inform you as soon as a new firmware is available!
Just tap on the Smart Lock connected to the Door Sensor in the Nuki app and open the lock's settings. Select "Features & Configuration" and then "Manage Nuki Door Sensor".
Tap on "Firmware update" to check for a new version. To perform the firmware update, simply follow the instructions in the Nuki app.
Note: To update the firmware, you need to be within Bluetooth range to your Nuki Door Sensor.