A "Check Sensor" message may occur if the sensor tip is not under your skin. Try to start your sensor again. If your reader displays “Check Sensor” again, your sensor was not applied properly. Remove this sensor and apply and start a new sensor.
To report a FreeStyle Libre 2 sensor that lasted for less than the 14-day wear duration please complete the online sensor support request form or contact our Customer Care Team at 855-632-8658.