If your Polar device (M400, M430, M450, M460, V800, A300, M200) fails to sync with the Polar Flow app, try these steps in order to fix the problem.
1. Make sure Flow app is running on your mobile device and keep it at the foreground.
2. Turn Flight mode on and off in your Polar device and see if it helps. Repeat the steps to turn it off again. Try the sync again. Continue with the steps if this did not help.
3. Reset Bluetooth connections from your Polar device.
4. On your mobile device, go to Settings / Bluetooth and make sure Bluetooth is set ON. Remove your Polar device from your mobile device's Bluetooth setting menu. Note! This step is important, especially with iOS devices since new device pairing can't be done in the Flow app before the earlier connection has been removed from the Bluetooth device list.
5. Turn off Bluetooth from your mobile device.
6. Sign out from the Flow app and uninstall it from your mobile device.
7. Restart your mobile device.
8. Turn Bluetooth back on in your mobile device.
10. Pair your Polar device with the Flow app by pressing and holding the BACK button until ‘Searching’ is shown on the display. Wait a while and enter a PIN code your Polar device suggests to your mobile device. Do not use your phone’s Bluetooth menu to pair the Polar device. The pairing is done in the Flow app!
If connection still doesn't work, perform a factory reset to your Polar device. See the user manual for your Polar device how to perform a factory reset.
If you are using Android version 6.0 or later, make sure location is enabled for Polar Flow app in the phone's application settings.
If you have several Flow app compatible Polar devices in use, make sure you have selected the one you are trying connect in the Flow app when trying to pair/sync the device with the app.
Please notice that the sync may take a while if you have lots of activity and training data on your Polar device.