Dexcom G6 CGM Troubleshooting


If you receive Dexcom alerts for Signal Loss, Sensor Error / Sensor Failed, or No Readings, these tips and troubleshooting steps may help. 

Types of error messages:

Sensor Error / Sensor Failed / Replace Sensor
  • These errors can occur if your previous sensor session wasn’t ended and the transmitter still trying to connect to old sensor. To disconnect from your old sensor, select Settings in the Dexcom app > scroll down to the bottom and select Stop Sensor in your Dexcom app.
  • These errors can occur if the transmitter is not fully snapped in. Make sure the transmitter is fully seated in the CGM cradle by pressing down firmly on the larger end until it clicks into place. You'll know the sensor is fully seated when you hear two clicks and the transmitter sits flat within the clear walls of the sensor.
  • These errors are not caused by the transmitter (except in cases where the transmitter has expired).
Signal Loss: 
  • This error can be caused by the transmitter being over 20 feet away from your display device, a bug in your phone operating system, your transmitter not being snapped in, or an issue with the transmitter.  Please follow the tips & troubleshooting steps below and if the issue does not resolve after 3 hours, please contact Support.
No Readings: 
  • This alert means the sensor is temporarily unable to measure glucose. Please follow the tips & troubleshooting steps below and if the issue does not resolve after 3 hours, please contact Support.

Tips before troubleshooting:

  • Your phone must be kept within 20 feet of your CGM. Avoid physical barriers like walls, water, cement, and metal. 
  • Keep Bluetooth pairings in your phone to a minimum. The pairing in your Bluetooth will say “not connected” and this is expected. This is because Dexcom G6 transmitters connect, send data, and disconnect every 5 minutes. 
  • The Dexcom G6 app should never be closed. Keep any additional running apps to a minimum in the background. High-intensity apps, like mobile games or video sites, draw large amounts of processing power and may cause signal loss.
  • Keep your phone charged. If your phone goes into low power mode, that will turn off Bluetooth and cause connection issues with the Dexcom G6 app and transmitter..
  • Your CGM transmitter holds 3 hours of data. After 3 hours, there will be glucose data gaps in your graph.
  • If your Dexcom app has lost connection for any reason, continue to log your food and activities in the Levels app in real-time (even if it hasn't received the data from Dexcom yet). The Levels app will process the last 3 hours worth of data as soon as the connection is restored.
  • If you recently switched time zones, check your phone to see if it is set to the correct time. If it isn’t, update to the correct phone time as this can prevent your data from uploading to the Levels app.

Troubleshooting steps:

  1. Make sure the transmitter is fully seated in the sensor cradle within the CGM by pressing down firmly on the larger end until it clicks into place. Ensure that the transmitter is flat inside the sensor. If it's sticking out at all, this could cause connectivity issues. When you install the transmitter you should hear 1-2 clicks to ensure it's seated properly and well connected.
  2. Ensure your location settings are turned on in your phone.  [instructions for how to turn on location with iphone / for android]
  3. If you have replaced an old sensor, disconnect from the old sensor by selecting Settings in the Dexcom app > scroll down to the bottom and select Stop Sensor in your Dexcom app.
  4. Make sure your phone’s Bluetooth is on. If it’s on, turn your Bluetooth off and then back on. Wait 10 minutes. If your signal does not reset, proceed to step 2.
  5. Make sure your phone has enough power. Bluetooth gets turned off in low power mode for some phones.
  6. Ensure the phone’s Bluetooth is paired with the CGM transmitter. Check that your Dexcom transmitter is in the list of paired devices in your phone’s Bluetooth settings. If it isn’t, delete existing transmitter Bluetooth connections from the phone, and then repeat the transmitter pairing process.
  7. Restart your phone and reopen the Dexcom app. Close all background apps before following this step.
  8. Enable Sharing settings in your Dexcom app. Open the Dexcom app > from the Dexcom home screen, tap the Share button in upper left-hand corner > you'll be asked to invite a follower, which you can just send to a personal email address, toggle the sharing button off then back on. This should reset any Dexcom app to Levels app connectivity issues.

If you continue to have connection issues after completing the troubleshooting steps, please email the Levels Support team at

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