But I wasn’t restarting….why the error??

Last night, we had a bleeder on a new Sensor #1.  A couple hours into its session, the sensor was losing data and just plain struggling.  Anna also said it was hurting a bit.  With those symptoms all together, we opted to pull Sensor #1 and put in a new one.

I called Dexcom to get it replaced while she put on her new Sensor #2 for the night.  Not long into warmup, about 35 minutes, the dreaded “Replace Sensor Now” message popped up accusing us (incorrectly) of trying to restart an old sensor.  (Turns out a lot of people have been having this happen to them, too.)

Anna thought it was weird, cleared the message without telling me, and tried restarting the warmup again.  Same message after another 35 minutes again.  At this point, she woke me up and told me she was having troubles.  The screen on the app was taunting us to start a new sensor, but that just didn’t sit right with me.  This was a NEW sensor.  It was about 3am now.  The last thing I wanted to do was:

  • Call Dexcom again,
  • Waste a brand new sensor,
  • Have to do a third sensor insertion, or
  • Dig out a transmitter from the brand new sensor.

So, instead I told her to just go to bed, and we left her app screen asking for a new sensor.  I grabbed the receiver out of the closet where we store it normally (we don’t usually use a receiver except for restarts).  I started a new session on the receiver, without even having the receiver connect to her transmitter first like I normally do when we are doing Option 1 restarts.  I just entered the sensor code for Sensor #2 that was still on her body, started a new session, put it in the faraday bag and went to sleep.  (If you don’t have a faraday bag, then you can keep the receiver out-of-range of the transmitter simply with adequate physical distance or by shielding it in a good microwave for the two hours.)  When I woke up about 4 hours later, I took the receiver out of the faraday bag.  It was showing “no data” and “signal loss” (like this old screenshot).  Exactly what I expected and wanted to see.  The receiver had stayed out-of-range of the transmitter for the whole warmup time.


Within 5 minutes, the receiver connected with the transmitter and was showing the last part of the warmup circle.  Also exactly what I expected and wanted to see.

And then 5 minutes after that…voila, receiver was showing its first BG value and my new Sensor #2 was no longer “needing to be replaced”.

So…the question is “Why would a brand new sensor be failing as if it is a reused one?”  I have heard from some people that Dexcom tech support is telling them that the sensor needs to pick up the “signs of trauma” that are expected from a recent insertion.  If the insertion doesn’t produce that kind of scatter and trauma in the data, the algorithm decides that this is a reused sensor.  It would appear the algorithm checks for this sensor scatter at 35 (or 65?) minutes (as that is when the “replace sensor now” messages pop-up).  By keeping the entire warmup period shielded from the transmitter, you bypass those scatter checks and can finish the startup.  I have no idea if all of this “trauma insertion check” is the truth…but that’s what Dexcom is telling people and it actually sounds plausible to me based on the observations.

The real problem is for consumers…we (and Dexcom, too) are having to be inconvienced as part of this “trauma detection” issue.  Pulling perfectly good sensors will cost Dexcom and/or the users money that doesn’t need to be spent.  And, even if the G6 doesn’t hurt for insertion (your experience may vary), nobody wants to have to do another pull of fresh adhesive off their skin unnecessarily.  Ouch.  Plus, Dexcom tech support is spending time answering phone calls about perfectly good sensors that are being rejected…adding wait times for us all unnecessarily.

So, until the “issue” is resolved (which I wouldn’t expect given the required FDA-approvals that went into this product’s design)…I highly recommend just pulling out your receiver and doing the restart like I’ve described above if you experience the same issue on a new sensor.  Save yourself the call to tech support, save yourself the new insertion, save the hassle.

Side Note:  This also confirms another nugget.  You could do this same procedure to restart an old sensor in the event you forgot to start the restart process in time.  Instead, wait for the session to end, then do this procedure that I’ve outlined above.  You’ll be able to restart an old sensor.

Side Note #2:  Based on what we know so far, I expect that a person who does not have a receiver could also just do Option #2 and restart similarly.     I haven’t tested it, but it would seem probable to be successful so long as there is no communication with the transmitter during the warmup.

6 thoughts on “But I wasn’t restarting….why the error??”

  1. I use my iPhone as a receiver. Wouldn’t it work to just turn off the bluetooth during the startup? I am on my first sensor so I haven’t had this happen yet.

  2. I tried two restarts using your Option #2 and got the NO RESTARTS message on both. I assumed Dexcom had made this change in their last software update to combat the extra time users are desperately trying to get from their sensors for financial reasons. I was frustrated and angry.

    Maybe I was wrong? I was anxious to see what you thought…

  3. Worked like a charm! We have a pump and phone so couldn’t connect reciever… so we started the session on the pump and put the phone to sit in microwave 2 hours … perfect! Wish I knew this yesterday when we disposed of a sensor that wouldn’t work … thank you!

  4. Aha…wish I had seen this post a few minutes before I pulled out a perfectly good new sensor and replaced it with another sensor! I was unwilling to wait for 24 hours or more for a call back from Tech Support, as I rely on my sensor to alert me to hypoglycemia. I will see what Tech Support tells me, but here’s my theory: My first box of sensors contained three sensors that all have the exact same code. So, when I get that “No Restarts” message, it is because the receiver can’t distinguish my new sensor from the old one with the exact same code. I get a 3 month supply at one time, and just checked through my boxes to see what codes I have. In the other two boxes, I have at least two sensors with the same code, and one is different. I will update once I get to talk to Tech Support. In the meantime, the tips you gave will help if I encounter this problem again!

  5. I am responding to the Article, “But I wasn’t restarting- why the error”. Wow, thank you so much for the insight. I was having this problem which I never had with the G6 until now. I followed what you did and am so appreciative for the advice as I finally got my CGM to get thru the warmup.

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