| Sensor Wear Duration | 10 days + 12-hour grace period |
| Warmup Period | 30 minutes |
| Failure Rate (user-reported) | ~5β10% |
| Replacement Policy | Free within 30 days of failure |
| Support Line | 1-888-738-3646 (24/7) |
| Operating Temperature | 59β77Β°F (15β25Β°C) storage |
Key Takeaways
- Dexcom G7 sensors have a reported failure rate of roughly 5β10% based on user data.
- Most failures trigger a "Sensor Failed" alert β the sensor must be replaced immediately.
- Dexcom replaces failed sensors free of charge within the warranty period via their 24/7 support line.
- Proper insertion site, skin prep, and warmup compliance reduce failure risk significantly.
What Is a Dexcom G7 Sensor Failure?
A Dexcom G7 sensor failure occurs when the sensor filament cannot produce reliable glucose readings, prompting the app or receiver to display a "Sensor Failed" error. Unlike a "Signal Loss" or "Sensor Error," a failed sensor cannot recover β it must be discarded and replaced. The G7 sensor is designed for a 10-day wear period plus a 12-hour grace period, but failures can occur at any point during that window.
Common Causes of G7 Sensor Failure
Insertion Issues
- Hitting scar tissue, muscle, or a blood vessel during insertion
- Inserting into an area with very low subcutaneous fat
- Kinked or bent filament after insertion
Adhesion & Site Problems
- Sensor lifting or partial detachment causing filament movement
- Excessive moisture, sweat, or early adhesive failure
- Applying over lotions, oils, or hair
Warmup & Calibration Errors
- Moving too much during the 30-minute warmup period
- Rapid glucose swings (>3 mg/dL per minute) during initialization
Device & App Issues
- Bluetooth interference causing data gaps misread as failure
- Outdated Dexcom G7 app version
Dexcom G7 Sensor Failure Alerts
| Alert Message | Meaning | Action Required |
|---|---|---|
| Sensor Failed | Sensor is unrecoverable | Replace sensor immediately |
| Sensor Error | Temporary signal issue | Wait up to 3 hours before replacing |
| No Readings | Connectivity or warmup issue | Check Bluetooth; wait 30 min |
Step-by-Step: What to Do When Your G7 Sensor Fails
- Confirm the failure: Open the Dexcom G7 app β if it clearly states "Sensor Failed" (not "Sensor Error"), the sensor cannot recover.
- Remove the failed sensor: Press the adhesive edges and peel off gently. Dispose of safely.
- Prepare a new site: Clean with an alcohol wipe, let dry fully for 60 seconds. Avoid previous insertion sites.
- Insert a new sensor: Follow the standard G7 insertion process, press firmly, and begin the 30-minute warmup.
- Contact Dexcom for replacement: Call 1-888-738-3646 or use the Dexcom app's "Report a Problem" feature. Have your sensor lot number ready.
How to Get a Free Replacement Sensor
Dexcom's warranty covers sensor failures under normal use. To claim a replacement: note the lot number printed on the failed sensor's applicator, take a photo of the failed sensor if possible, and contact Dexcom Support within 30 days of failure. Replacements are typically shipped within 3β5 business days at no cost.
Preventing Future Sensor Failures
- Rotate sites β abdomen, upper buttocks, and back of upper arm (approved sites)
- Use a skin-prep wipe or medical adhesive barrier before application
- Avoid vigorous activity during the 30-minute warmup window
- Keep the Dexcom G7 app and phone firmware updated
- Store unused sensors at room temperature (59β77Β°F / 15β25Β°C)
For reliable CGM supplies and accessories to protect sensor adhesion, explore MDS Diabetes β including skin-prep wipes, adhesive patches, and G7-compatible accessories designed to extend wear reliability.