What do ???? mean and how long before they go away?


you need to restart your sensor

It means that the transmitter is having trouble communicating with or interpreting the sensor wire. Usually this happens in the clips aren’t fastened properly and moisture gets under the transmitter, if your clothes are rubbing on the sensor, if you sleep or sit funny putting pressure on all or part of the sensor, or any number of other reasons. I usually check my clothing and try to relieve any rubbing or pressure; sometimes I jiggle the sensor a bit to try and help the wire find a happier position. All you can really do is wait. If the ??? doesn’t go away in 3 hours or less, call Dexcom and they will probably tell you to replace the thing and they’ll send you a new one - even if the ??? was likely a result of user error and not a malfunctioning sensor. Good Luck

CC said it perfectly, ??? appears when the Dexcom receiver cannot make sense out of the data coming from the transmitter attached to the sensor. You don’t need to stop nor restart the sensor in this case, just wait until the situation that caused the “confusion” is cleared, typically in a couple of hours you should be fine.

It could be moisture, but it could also be contradicting readings from the sensors.

Only if the ??? persist for long, then I would call Dexcom and explain them what happened.

Ciao, Luca

For the first time yesterday, I got the ??? in the middle of the start-up period. I was concerned about what that would mean for the accuracy of the sensor once I got it going (the ??? did go away in about an hour). Luckily, it seems like it didn’t really effect it. It was really comfortable so I was glad I didn’t have to rip it out!

In my experience, Dexcom makes you wait three hours for the ??? to disappear. If it doesn’t, and you’re within a week of inserting it, they’ll send you a new one for free.

I posted a fairly recent thread called “Fun and games with sensors” that describes close to a week straight of intermittent ??? readings. All that time, I did not restart or recalibrate the sensor other than when prompted.

Still not sure what happened to cause the sensor confusion. The site was a bit inflamed when I removed the sensor and I did manage to trap a piece of hair underneath the transmitter when I restarted it after the first week. Other than the ??? readings, the sensor gave good numbers up until it finally just crapped out on day 13.

The only time I got ??? was the first time I started with the Dexcom. I don’t think both sides of the sensor were locked in and every time I got out of the shower it would show for an hour or so and then start working. It was definitely getting wet. Haven’t had it happen since and I’ve gone snorkeling. Make sure the sensor is locked in well.