Dexcom G5 won't allow iPhone to pair/sync

Hello! First post!

I’ve been using a Dexcom and just upgraded to the G5. I had everything set up, but wound up deleting the app from the phone (as I wanted to reset my account information to sync it with WatchSugar for the Apple Watch). So I’ve reinstalled the G5 app on my phone, but can’t get it to complete the setup. When I get to the second last step/window, it asks for my transmitter SN. I enter this and get the following pop-up message:
"This transmitter is already paired with another device. A transmitter can be paired with only one Dexcom G5 Mobile app at a time."
I’ve reached out to Dexcom support, but got an email back saying they’ll respond "in a few days."
Has anyone else encountered this? Any workarounds? Is there a way to get out of the setup wizard, as I suspect that getting past that, would be all that’s required.
I really don’t want to do a complete wipe of my phone and am keen to get using this quickly. Any suggestions would be very welcome.

we have several discussion topics here on that - I used the magnifying glass (upper right) and found this recent one

Not exactly sure what happened in your setup, but you may try the following: on the iPhone go to Settings, Bluetooth. If you see a Dex among the devices, tap on the circled “i” and then on the “Forget This Device” tab. Then, you can re-try to complete the setup.

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Thanks for the suggestion. I did give that a go but still get the message. It appears the Bluetooth settings have been retained by the phone and I’ve tried (unsuccessfully) to flush it by resetting the Network Settings (which, I found, doesn’t extend to wiping Bluetooth data). I suspect that if I could just find a way to get beyond the app’s setting wizard that I’d be fine.

Indeed, resetting Network Settings does not affect Bluetooth. Does the Dex still show up among bluetooth devices even after you’ve tried to forget it? In any case, I’d try to get back to a clean initial state - remove all apps that may have anything to do with Dex, if Dex still shows up among bluetooth devices, try to forget it again. Then reboot - power down and power up iPhone, or just turn off and turn on bluetooth, then re-check bluetooth settings - make sure no Dex device shows up there. Then, reinstall the app and try to go through the setup again. Good luck!

Thanks for the further suggestions. All tried, but no luck. I’m kicking myself, and wished that I’d backed up my phone before installing the Dexcom app, as I’ve got a ton of new photos apps etc, since the last backup. Otherwise I’d do a restore…but I’m running out of options. Will sleep on it before doing something so drastic. Hopefully Dexcom support will respond in the meantime with an easy fix!

Hmmm. Been doing more trial-and-error and found that if the wifi isn’t connected, you get a message saying “Currently you are not connected to the internet. Please try again later when you have internet access.” So I’m wondering if it may be an issue that can be resolved by resetting it on Dexcom’s servers.

I’d not wipe the phone because of this. If Dexcom tech support can’t suggest an easy solution, just ask them to send you a replacement transmitter - that should fix the problem regardless of what the root cause may be. You may also post your question elsewhere, e.g. at

Am on the phone to Dexcom support now. The second I started describing the issue, the rep knew exactly what I was talking about and said they can reset it at their end. That’s a relief. Am on the phone now with a tech support rep, who is releasing it. Hopefully this information will be useful to anyone else who inevitably stumbles into the same issue!

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So, after a 42 minute call to Dexcom, they’ve managed to release the transmitter, so I could re-pair it. To be fair, there were complications as the reps were unaware that there’s two different tools to be used, depending on whether the user is in the US or outside the US (which I am). In any event, all good now!
Thanks for your suggestions, Dragan1

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Another update:
A big reason I upgraded to the G5 was the promise of having my blood sugars on the Apple Watch. After I saw their early prototype a couple years ago, I decided to buy the watch, thinking that workable software would soon follow. Then came the announcement that Apple Watch wouldn’t be part of a G4 solution, so there was another wait. The arrival of an Apple Watch-capable solution took awhile longer than expected, but when it was finally announced, I thought “Fantastic! I’m ready!” and upgraded to the G5.
Except that it’s still not here.
While the announcements finally came, it wasn’t clear that non-US users would still have to wait. So having upgraded and installed it, I’m disappointed (again) to see that non-US, mmol-using CGMers will have to wait awhile longer (and with no sense of when it’ll arrive).
Incidentally, I upgraded but waited for my G4 transmitter to die, before switching to the G5. The G4 transmitter was amazing. It was in operation more or less constantly for 1 year and 2 days before finally flashing up a message saying the battery was done. Hat’s off to Dexcom for creating such a wonderful, tiny and durable solution.
It’s also been interesting to see how many dropouts the G5 transmitter has, vs. the steadier G4.

I do have to say, I love Dexcom’s technology and appreciate their innovation. I’m just frustrated at the unevenness of its rollout to international users and the ambiguity around when the technology will be available outside the US.

It’s a problem with Bluetooth. There are a limited number of channels available for it and it can get bumped if a stronger device is trying to use the one your CGM is on. I’m guessing the transmitters are just not that strong, since battery life is a big issue. Some people recommend checking the list of Bluetooth devices on your phone (or watch) and disconnecting any that you don’t need. As for sources of interference, this is from an audio site but it’s still a handy list of all the things that can cause problems:

Interesting, DrBB. Thanks for sharing that.

No, it wasn’t due to a new account. Dexcom had to “release” (for want of a better term) the transmitter from the server and allow me to reset it on their system…or something like that.

Grrr. I’m here because I tried to install a new G5 transmitters. I’ve been through about a half dozen or so now and never had a problem with my phone and connecting them. I tried removing the app, clearing out all of the Bluetooth items on the phone (only had a couple old G5’s but different names on each) I made sure no local bluetooth items were in the area. (same room I always install them and pair them in anyway) tried a second sensor but nothing would work. I then called tech support and they asked if I did these things and then asked if I’d try again(?) so I did. (Just the pairing/removing the bluetooth item from my phone, restarting the phone, removing adding the app) After 30 min he called me back and we found it still wouldn’t. So he sent me a replacement for the two sensors I’d tried and the transmitter. (RIDICULOUS amount of waste for the return packaging by the way, they should be ashamed) Today I got the replacement, and went through the whole process again and it Still won’t pair? So I was reading here, hoping to find others who also couldn’t…and then thought I’d share what they had me do and also vent ha! thanks. Good luck. Guess I’ll just try again after I research more

Thus far I pretty much consider its ability to consistently and reliably pair to the iPhone to be pretty much a farce

I found this which didn’t offer much more but some. I’d only been doing a swipe to shut down and then start it back up until just now. I followed the first direction of a Hard Boot which is holding down the home and the power button until it shuts off and starts back up. I tried again and it instantly connected.

If one doesn’t use a phone at all with the G5 do they need to manually upload their data from the receiver into clarity or does that happen automatically somehow?

If you don’t use the phone, you need to plug the receiver into your computer and manually upload.

Does this include the receiver itself? Is it possible the receiver and the phone are fighting over the channel? And the receiver is winning ?