Dexcom G6 CGM troubleshooting

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

Signal Loss Alert: 
  • 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. Follow the troubleshooting steps below and if the issue does not resolve, please contact support. While troubleshooting, if you discover that the transmitter is not fully snapped in and snapping it in completely does not clear the error after 3 hours, please let support know.
No Readings Alert: 
  • This alert means the sensor is temporarily unable to measure glucose. Please follow the troubleshooting steps below and if the issue does not resolve after 3 hours, please contact support for a replacement sensor.
Sensor Error: 
  • Your transmitter is communicating with your display device but is unable to detect the correct glucose value. 
  • Sensor errors can occur for several reasons, but this error is not caused by the transmitter (except in cases where the transmitter has expired). 
  • Sometimes this error can occur if the transmitter is not fully snapped in, so we recommend checking that the transmitter is flat against the sensor. If this error persists for 3 hours, the screen will say "Sensor Failed" and support can assist you with a replacement sensor. 
Replace Sensor Now: 
  • This error message may pop up if you haven't clicked the transmitter fully into the CGM. 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 
  • If you replaced an old sensor with a new one, this error message will pop up if the old sensor hasn't been disconnected yet. To disconnect the old sensor, select Settings > Stop Sensor. 

A few 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. Note: Dexcom G6 transmitters connect, send data, and disconnect every 5 minutes. The pairing in Bluetooth will say “not connected” and is expected.
  • 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.
  • Make sure nothing is pressing on the CGM, like a waistband or seatbelt.
  • Always clean the back of the transmitter with an alcohol wipe before attaching it to a new CGM.
  • 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.

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. 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.
  3. Make sure your phone has enough power. Bluetooth gets turned off in low power mode for some phones.
  4. 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.
  5. Restart your phone and reopen the Dexcom app. Close all background apps before following this step.
  6. 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

Did this article answer your question? Thanks for the feedback! There was a problem submitting your feedback. Please try again later.