It could be a sensor placement issue, but my last one was squirelly, so I'm wondering if maybe the transmitter needs replacing. Does this sometimes happen with a transmitter that is at the 6 month mark, or does the receiver usually catch it and give good warning?
We're about 8 months now and our transmitter is still going strong. We have had times like that and it turns out it was just a bad sensor or bad site. I would keep using it until you get the low transmitter battery sign.
I am assuming that you aren't doing anything different like more exercise.
My brand new transmitter of less than a month bit the dust this week (the one before it lasted a year and gave me a low battery and order new transmitter warning at least 2 weeks before it gave out).
I was getting a lot more than usual "out of range" error messages over 2 weeks with the new transmitter before it finally stopped working altogether with no other error messages.
Dex tech support originally said it had to be a receiver error until I revived my old receiver and got the same message. they over-nighted me a new transmitter. They also said that the exceptionally cold weather we are having in the northeast could affect the system after going in and out of the cold - don't know if this helps.
My first transmitter lasted 11-12 months, and definitely had similar issues during the last month. As soon as I switched to new transmitter, problems gone.
I switched when the low battery message appeared, since I was curious to see how long before it would appear. It was just under 1 year for 1st transmitter. Next time I'll switch when it starts getting squirelly - I had many ??? lasting 1-2 hrs, and less accurate readings during the last month.
There are similar threads on this.
I just replaced the transmitter on my G4 this past week. The original lasted a little over 12 months. I got a message saying the transmitter battery was low and three days later my receiver starting showing I was "Out of Range" even though the transmitter and receiver were ten inches apart.
I had the same problem with the hourglass coming up a couple days after putting in the new transmitter. It came up while I was taking a shower. More than likely it was moisture related then cleared up about an hour later.
It appears the transmitter just dies and you get nothing. I don't believe the ??? and hourglass are related to the transmitter battery.
If your insurance covers it, I would go ahead and get it replaced. We made the mistake of waiting until it said the battery was low (after experiencing what you are describing) and then it died completely in about three days. So we were without anything for a couple of weeks waiting for another script, approval, etc.
I've only had the ??? and hourglass warning once. It occurred when I calibrated a new sensor and my fingerstick number was well off the display number, like 50 points or more. Then it requested another calibration 15 minutes later. I gave it another number and the display responded with ???. I gave it another calibration number about 30 minutes later and it responded with a number relatively close to my fingerstick number. I later terminated this sensor when I continued to get unreliable numbers. When I pulled the sensor/tape off, there was blood on the sensor tape. The sensor must have been fouled with blood right from the start.
My son's first transmitter only made it to 8 months. We started getting the hourglass and ??? symbol constantly with NO low battery warning. We went through about 5 sensors before support suggested that it could be the transmitter. The day we snapped in the new transmitter all the problems were gone. Just an FYI.