Troubleshooting tips for the G6

I’ve been using Dexcom’s G6 for 2 months now, and after many calls with Dexcom support I learned a couple tricks that are not explained in any documentation, so I wanted to share them here.
I’ll post the 2 tips, and explain all the details below for anyone interested:

Tip #1: It’s best to avoid taking a photo of the sensor’s QR-code with your phone. It’s safer to just manually type in the 4-digit sensor code

Tip #2: You need to wait 5-10 minutes between stopping an old sensor and starting a new one!

Before learning about these, I would often start a new session and after 2 hours it would ask me to calibrate daily!
The first time this happened I had taken a photo of the new sensor’s QR-code (since that seemed fun!) and Dexcom support told me “that was probably the issue, those are very picky and if they don’t work the sensor just continues as if it didn’t get a proper sensor code.”
Again, I really think Dexcom should post this somewhere… as I don’t see anything about these… or even better: the App should tell you “I didn’t get a proper sensor code, please try again” instead of doing nothing and wasting 2 hours and then, ultimately, a sensor.
(Because in all these cases Dexcom replace my calibration-required sensor).

The second time I followed Tip #1 and entered the sensor code manually but still had to calibrate after the 2 hour warm up, and then daily from then on.
This time Dexcom asked “how much time passed between when you stopped the previous sensor session on your phone and started the new one?”
I explained that I stopped the session, inserted the new sensor (which is super fast now), and then removed the old transmitter and inserted it in the new one. Probably took 2-3 minutes total.
The Dexcom rep explained: “if you start a session before the previous session registers as being stopped… then it messes things up. When you hit ‘Stop Session’ on your phone, it takes a while to tell the transmitter that information, and so you should wait 5-10 minutes to be safe.”

So, even since then, I always enter my code manually, and always end my sensor session well in advance of inserting the new one (I remove my old sensor, clean the site, etc) before hitting the “Start New Session” button on my phone.

I hope this helps anyone else who had these issues, for me there is nothing more frustrating than having a G6 that asks me to perform a fingerstick calibration… I don’t ever want to do those again :slight_smile: I went from testing 10 times a day with the G4 to sheer bliss with the G6!


Thanks for this. I have not run into these issues but when you took the pic of the code, did you get the green check mark? And it still asked you to calibrate?


Thanks !!!

Nice tips along with the explanations.

The first ever time I used the G6 I took a photo and everything went fine.

It was on my second sensor where it had issues (but it could also have been that I didn’t wait long enough between sensors), and indeed I got the green check mark, the 2-hour warmup went fine, but my G6 basically turned into a G5.

Because those were the 2 “bugs” that multiple Dexcom reps told me about, ever since then I always type in my sensor code manually (I think it might take me 1-2 seconds longer than the photo ;-)) so I don’t have any cases where I took the 5-10 minutes and used a photo… though I’m sure it would work most of the time (or Dexcome would get a lot more calls!).

I just don’t want to take that chance, because one of my favorite aspects of the G6 is not having to calibrate after the 2-hours of being “blind” to my sugar numbers.
It was always stressful when the end of the 2-hours would coincide with being in the car, or a movie theatre, or while I’m in the middle of teaching a class!

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I’m thinking the photo aspect is not the issue but the 5-10 minute wait is what is the true cause, which then requires you to calibrate.

I’m on my 4th sensor, took a photo every time of the code, and I always let my sensor expire on its own. By they time I notice it and see the expired alert on my watch 5-10 minutes has already elapsed.

I wouldn’t give up on the photo - it will reduce errors in entering a code.

You’re probably right, as long as it’s a nice clean photo.

I think the Dexcom reps mentioned that some people took the photo through the plastic carton (before taking off the wrapper), which is Dexcom recommended typing it in manually.

I might take your advice and be brave next time :stuck_out_tongue:

On the G6, we have the app running on the Apple Watch. With the G5 the cgm number displayed. But for some reason the Dex cgm BG number is not showing with the G6 on the watch face. Tried reinstalling the watch app. Or watch face. Or whatever it is called. I don’t wear it. lol.

Anyway - Any tips or known things that need to be done to make it work?

We were going to mess around with it but if can’t get it to work then give Dex Tech Support a call tomorrow and work the issue with them.

But maybe somebody already has the process.

I had the same issue. This is what I did.

Uninstall the G5 and G6 Apple Watch app, from the watch settings. Do not uninstall the phone G6 app.
Shutdown the watch
Start the watch.
Install the G6 app on the watch from the watch settings.

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Thanks. We tried similar but not exact. We will try exactly the same steps and see if that resolves. Appreciate it !!!

@Anthony, Followed your steps. (Thanks again.)

So it is better now. The app or gadget or whatever it is (lol) is on the watch now. Flick the wrist, hit a button and the Dex 6 cgm graph and number show up.

However when on the G5, with just a flick of the wrist, the cgm number (but no graph) would show right up on the watch face. The big benefit of this is that during class (or meetings - whatever) you can see your BG with just a flick of the wrist that nobody else would even notice. Especially in school there is such a big deal about “no cell phones - no texting” because how badly so many people abuse these and just chat/txt/whatever during school.

So, do you have the BG itself right on the watch face which is visible with simply a flick of the wrist and no further need for interaction or button push or anything? Is this maybe a different watch face or configuration that is required?


Yes, you are talking about what is called a “complication”. Its a feature where you can add certain apps to your main watch face. You will need to go into the watch app on your phone, look under “Complications” and enable the G6 there if it is not already.

Then edit one of your watch faces and set one of the gadgets to the G6 complication. That should fix it.


Got it working.
(Obviously I don’t wear the watch - ha ha ha)

The one issue that was initially confusing is the Dexcom G6 complication (hope I use the term proper) does not show up in the list for all areas for all faces. Top/bottom/left/right/middle - depending on the watch face, some of them allow the Dexcom G6 and some do not have it in the list.

So when we were first looking I guess we picked one where it was not allowed so thought it was just not working at all.

I assume there is some logic as to why/when it is included in the list but we picked a face and got the Dex added and now it shows up on the watch face.

So thanks very much for the assistance !!!

I will be switching to G6 in a few weeks. If I’m not using phone, these issues are moot? Or is there still the stop/start issue?

Thank you so very much for sharing these two tips. I will try them as soon as this sensor expires next week.

I was confused too when first seeing that term. You would think they could have picked a better name.

So I’ve been taking photos again since September 2018 and was fine until this week… when it happened to me again: now I have to calibrate for the next 10 days :frowning:

I called Dexcom and the very first thing they told me was “don’t take a photo… it rarely doesn’t work, but when that happens it doesn’t warn you that the code did not get registered”

Hopefully they will fix that bug so that either the photo get accepted, or it warns you that it didn’t so you can enter it manually!

It’s a horological term. I think it’s kinda cool that they use it even though it’s originally from mechanical watchmaking, but then I’m a total word & etymology geek:

Geez, now I need to look up horological.