This may mean that your sensor was already started by another device. Both the reader and app can only be used with a sensor that it started. Try checking your glucose with the device that started it or apply and start a new sensor.
If the “Sensor Already in Use” display message persists after repeated attempts to scan your sensor please complete the convenient online sensor support request form, or contact Customer Care. Customer Care is available at 1-855-632-8658 7 Days a week from 8AM to 8PM Eastern Time; excluding holidays.