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Phones & Tablets

How do I fix a FreeStyle Libre 3 sensor that will not activate on iPhone?

Answer

Confirm Bluetooth and Libre 3 permissions, force-close and reopen the official Libre 3 app, hold the top of the iPhone steady against the sensor to scan, then restart the iPhone if the activation screen still never appears.

Before you start: stop right away if…

  • Glucose sensor issues can affect diabetes management—follow your clinician's guidance and use backup meter testing if readings are unavailable.

Follow these steps

  1. Check Libre 3 permissions

    Go to iPhone Settings > Privacy & Security (and Settings > Libre 3) and allow Bluetooth (and any other permissions the Libre 3 app requests). Confirm Bluetooth is on in Control Center.

    You should see: Libre 3 shows permission granted and Bluetooth is enabled.

  2. Restart the app and scan steadily

    Force-quit Libre 3, reopen it, choose the activate/scan flow, and hold the top of the iPhone directly against the sensor for about 10–15 seconds without moving.

    You should see: The app detects the sensor and continues activation, or shows a specific error.

  3. Restart the iPhone and retry

    Restart the iPhone, open Libre 3 again (not a third-party shortcut), and repeat the steady scan at the top of the phone.

    You should see: The activation screen appears and the sensor pairs.

  4. Reinstall only if still stuck

    If the activate screen never appears, reinstall Libre 3 from the App Store, sign back in, and scan again. Contact Abbott's official Libre support if a new sensor still will not start.

    You should see: Activation works after reinstall, or official support can replace a faulty sensor.

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Extra tips

What to look for: Prompts to change or activate a sensor while the app never opens the activate/scan screen, or scans that fail to complete.

Before you change anything: Use only the official FreeStyle Libre 3 app from the App Store. Keep the sensor applied as directed in the product insert. Do not remove a working sensor solely to troubleshoot the phone unless the app requires a new sensor.

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