Reset G5 Transmitter

First, let me preface by saying that I adore, love, respect, and covet my Dexcom system.  It gives us a stability with type 1 diabetes that we would never be able to do without now.  But what I’m about to tell you is a bit of a hack on their system.

There’s been one thing I really have not enjoyed about moving from the G4 to the G5 system about four months ago.  The G4 transmitters were warrantied for 6 months, but usually the battery in those would go for a year…meaning we had the opportunity for much of the transmitter’s useful life to have a backup on the shelf at all times.  If the G4 transmitter failed for any reason, we could pick one off our shelf and not stress about how long it would take to get a new one.  Overseas travel and 2-week long diabetic summer camps were not a big deal…we could pack a backup.

Then we switched to the G5 system at the beginning of this year so that Anna didn’t have to carry a receiver while she did track team workouts.  This dramatically improved the likelihood that she would stay in good BG range during workout because our DIY loop system would have BGs available the entire workout to help her insulin needs.  If Anna had to carry a receiver during track workouts, that would’ve been the straw that broke the camel’s back in terms of diabetes gear she was willing to manage.

So, we’ve loved the G5.  It has worked well; not really having any problems with signal loss, BGs are accurate, we have enjoyed Clarity reports.  All good EXCEPT those G5 transmitters being shut-off by Dexcom  at 112 days.  At 90 days, you get a warning and your warranty is up.  At 112 days, your transmitter is artificially shut-off even though the batteries have some useful life left.  How much life?  Well, that depends, but for most users it is about a couple more months of life.

The problem with this system is that my insurance covers 2 transmitters in one order every 6 months.  So, for the first 90 days (3 months) after a transmitter order, I will nicely have a backup sitting on the shelf in case things go wrong.  BUT, for the next 3 months, I will have no backups on the shelf.  If that second transmitter dies early, I would have to wait for Dexcom to send us a new one.  If we were overseas or traveling, this could be very inconvenient.  I definitely won’t have one to send with Anna to her 2 weeks of summer camp based on how I can forecast our insurance refills already.

And here’s the really great news.  You can now reset the clock on that 112 day shut-off by building your own iPhone app.  This doesn’t buy you heaps of extra time…as the battery will only go for about 2 more months (maybe even less?) past 112 days…but that could be just enough time to start to be able to keep a backup transmitter on the shelf for longer between orders.

Another really good plus?  You can use this reset on G5 transmitters that have had their batteries replaced AND still use the Dexcom official app…you won’t have to try to use a different app (like Spike-App or X-drip+).

HOW TO BUILD RESET APP

What you will need:

  • iPhone (iOS 11.0 minimum)
  • (this may also work on iPod…but I haven’t tested it yet)
  • Apple computer (macOS 10.13.2 High Sierra minimum)
  • Xcode 9.3 (newer versions will work too…blogs are bad for “current” version references lol)
  • Apple ID email

Check to see if you need to update your macOS based on the version of iOS you have.  You can check your macOS by clicking the apple logo in your computer display’s upper left corner and selecting About this Mac.   If you are due for an update, click the Software Update button.

Download and install the app called Xcode from the App Store on your computer.  When the installation is finished, open Xcode by double-clicking on it from your Applications list.

Note: If this is the first time you are opening Xcode, you may get an initial message telling you that Xcode is installing command line tools.  Please let that run and complete the installation.  Command Line tools are a needed installation.

Go to the Xcode menu on the top of your screen, and click on Xcode and then Preferences...

Within Preferences, click on the Accounts tab and then the + button in the bottom left corner to add an account.  You are going to add an Apple ID type account.

Enter in your Apple ID email and password.  This process automatically makes a free Apple Developer account associated with your Apple ID email.  The account will show up in your Xcode preferences now with your name and (personal team) as a suffix in the name.  Once your account is added, close the Preferences screen by clicking on the red circle in the upper left corner.

Download the code for the ResetTransmitter app that we are going to build by clicking HERE

Open your downloads folder and navigate to the CGMBLEKit-master folder and then find the file CGMBLEKit.xcodeproj folder.  Double-click on that file and the project will open in Xcode automatically.

Click on the open button when the message appears asking:

“CGMBLEKit” is a project downloaded from the Internet. Are you sure you want to open it?

{Take the time now while the project opens to plug in your iPhone to the computer using your lightning cable.  Please accept any prompts about trusting your computer and unlock your phone so that it stays awake through the build process of the app that we are about to finish.}

Now click on the CGMBLEKit at the top of the left column, and then click on the small box as shown on the screenshot below to show the list of “Targets” below it.  Select the “ResetTransmitter” target.

Now, look at the screenshot above.  See that part highlighted in blue? You will need to change the loopkit part of the Bundle Identifier to a unique-to-you word.  Make sure that when you make the edit, you do not delete the period before and after.

Once you have the name edited, then go down to the Team section and select your (personal team) signing name from the drop down menu selection.  [Note: if you have a paid developer account, you can use that signing name instead.]

After you finish signing, a Provisional Profile will automatically be created and you’re close to done.

If you see a prompt under the status area below the Team about your device not being registered, please click on the Register Device button provided there to register the iPhone to your developer account (see screenshot below).

Now, navigate up to the top of your window and select two things; one from the left side of the box you’re going to select ResetTransmitter and from the pop-out, you’re going to select your phone’s name from the very top of the device list (not just your phone model…you want to go all the way to the top of the list for your phone’s name).


Stop and double check….most common mistake is forgetting to select ResetTransmitter as shown in the screenshot below and mentioned above.  Do not leave the selection on CGMBLEKit…if you do, your app will build properly nor will it appear on your phone.


If your phone/device name has (untrusted) after the name (see screenshot below), please open the phone and click on the Trust button that should appear on the main screen.  If the (untrusted) tag hasn’t disappeared after that, just unplug and replug the phone into the computer.  That should get rid of the (untrusted) tag.  If you try to build an app onto an “untrusted” device, you’ll get an error message reminding you to do the steps above.

When you’re done, the screen should look like the screenshot below; ResetTransmitter on the left, your phone’s name on the right, and no red error messages under the signing team area.  If your screen looks correct, then go ahead and press the build/play button.

Depending on if this is the first time you’ve built on Xcode, you may get prompts for codesign access and keychain access.  If those prompts appear, please enter your computer’s password and click on the always allow button to confirm.

Also, if this is your first time building with this developer account onto your iPhone, you may get another warning that the app could not launch because an issue with trust on your Developer Account on your phone.

Follow the directions on the warning.  Open your iPhone Settings >> General >> Device Management and then select your Developer App certificate and trust it.

Once you click the Trust on your iPhone, go back to Xcode, click on the blue OK button for the warning and then press the build/play button one more time.  This will finish the build of the app onto your phone.  Success!  You can unplug your phone from the computer and use the app now.

 

USING THE RESET APP

There is some warning messages in there about the use of this app.  When the app was first written, the code writers were uncertain how Dexcom Share and Clarity servers would treat information coming from a clock-reset transmitter (i.e., would data still be uploaded properly). The app has been in-use by many people now and the Share and Clarity services are, thankfully, not impacted by the reset transmitters.

You cannot reset a transmitter that is currently in a session and/or paired with Dexcom or Spike, or any other device/app.  So, stop any currently running sessions, and quit the dexcom app.   Forget the transmitter from your iPhone’s bluetooth list.  Forget all Dexcom transmitters from the list…no reason to keep old ones that you aren’t using anymore anyways. Re-open the ResetTransmitter app, enter your Transmitter ID and press the red Reset button.  Within 5 minutes you should get a pairing request.

If you do not get a pairing request and instead see a message “Unable to parse auth challenge: timeout” that means your transmitter is still busy with another app.  Double-click the iPhone’s home button and scroll through the open apps.  Upswipe on the Dexcom and the Reset apps to close them.  Restart the phone, re-open the Reset app, enter in the transmitter ID again and press the red Reset button again.  Within 5 min you should now see a pairing request.

If you STILL don’t see a pairing request, some users have reported that turning off Dexcom’s cell data within the iPhone Settings >> Dexcom G5 app can also help release the transmitter from Dexcom app’s influence.  If that fails…you can try deleting the Dexcom app and reinstalling it at the end of the reset process.

If you still don’t get a pairing request, make sure the transmitter is within pairing range of the iPhone (but not in active session).  The Reset app needs the transmitter close enough to be able to pair with it in order to reset the clock.

Once you press the pairing request, the reset command is immediately issued and you should get a confirmation screen like below:

You can now close the Reset app (double-click phone’s home button and upswipe Reset app) and forget the transmitter in the iPhone’s bt list again.  Reopen your Dexcom app and you’ll be able to use your transmitter for another 112 days or until the battery gives out…whichever comes first.

The free developer account that you signed the Reset app with only allows the app to be used for 7 days.  After 7 days, the app will simply produce a quick white screen and self-close if you try to open it.  You can rebuild the app anytime after the 7 days to use it again.  Simply double-click on the file in your CGMBLEKit folder download to open the project in Xcode again, plug in your iPhone, and press the build/play button.  All your previous changes will have been saved, so the rebuild is quite easy.

You can reset any amount of transmitters.  The app does not know transmitter ownership, nor does it have a limit on how many times you can use the app to reset transmitters.

The transmitter does not have to be on a sensor in order to be reset, just needs to have battery life left and not be paired already with another app.

39 thoughts on “Reset G5 Transmitter”

  1. Question??

    What kind of warning do you get after reset before battery dies if any? Wondering if you get a warning so you can get another transmitter ready to go.

    THANKS

    1. You’d get the same warning as before a battery reset had happened…the transmitter has a low battery warning coded into it, but because of dexcom’s artifical kill-date, you just normally don’t see it. If it’s anything like the G4, it is not much of a warning…but at least a little bit.

    1. I do believe that x-drip may have added that feature? But otherwise, nope…all the options are in the Apple/mac arena for resetting

  2. Thanks so much for developing and blogging about this this Katie! Just a quick question… do you know if Dexcom accuracy is affected by doing this? I’ve had amazingly accurate readings on Dexcom for just over three months, but since resetting the transmitter clock the readings from my sensor are between 15% and 20% different to the readings from my BG meter. It might just be a ‘bad’ sensor and nothing to do with the transmitter clock reset but just thought I’d ask.

    1. Transmitter clock wouldn’t affect the sensor readings/discrepencies…probably a sensor issue unfortunately.

      1. I’m having the same problem. Since the reset the last two sensors have been consistently +/-3mmol/L in error, even when calibrating three or four times daily, which is a problem I’ve never encountered in the last 2.5 years of using the G5. My clarity and diasend uploads have also been affected, with most of the data missing and only a few readings per day coming through. I’ll put in a new transmitter and let you know if anything changes.

    1. The transmitters are hard to drop a pairing from one app over to the other. Deleting the dexcom transmitter(s) from the BT list on the phone, restarting the phone, and then opening the app that you want to pair with…that’s the best troubleshooting for when it won’t pair within first 5 min.

  3. Has anyone tried to reset it with an ipad instead of with a computer? I don’t have an apple computer

    1. you’d still need an apple computer to build the app, even onto an iPad. If you have an iphone though, and no mac…you can find the Spike-app and do it through that. The spike app has the reset built in as an option https://spike-app.com/ instead.

  4. Hi – Thanks so much for publishing this code. My daughter’s last G5 transmitter just died and we’re waiting for insurance to clear the G6. I followed the instructions and the build succeeded, but I don’t see an app on the iPhone. It was plugged into the Mac and I didn’t see any errors like you mentioned in the instructions. Any thoughts on what to look for?

    1. Yup, if you can find me on FB, i’d be happy to walk you through a fix. I’d need to see a couple screen shots to know where the problem is.

        1. The issue is that you likely do not have the ResetTransmitter app selected to the left of where you selected your iPhone from the list of devices (near the top of the Xcode window). You need it to say ResetTransmitter, like the screenshots show.

        2. In particular, look at my screenshot that has the build/play button circled and pointed to…look just to the left of the circled build/play button on the screenshot and you’ll see the word ResetTransmitter. You need to get that selected correctly before you press build/play button…or you’ll get no app installed.

  5. This sounds awesome, but I had a question. I’m an Android user. I have read through the entire process. My super close friend has an IPhone and my other friend had a Mac that they will let me borrow in order to build this. After the reset, will I be able to use the transmitter on my android with the dexcom app? Also, I’m fairly Apple product illiterate…lol. Is the AppleID going to be an issue since neither the Mac nor phone is under my ID not the same ID? I was assuming AppleID was similar to a Google account where I could just sign into my friends computer using my Apple ID and sign into the phone using my ID and it would be okay? Please Help!

    1. Yes, you will still be able to use the transmitter on your android device after using this resetTransmitter app. Apple ID is not an issue…that is basically just (any) email address that Apple “knows” you by. So, you’d want to create your own Apple ID if you don’t already have one (that’s super easy). If you already have one, you just use your own Apple ID on the friend’s Mac when you get to the step for “adding your apple ID in Xcode preferences”. The Apple ID is only used by Xcode when you enter it there. And after the build, you can delete the apple ID from Xcode preferences if you don’t want it hanging out on someone else’s computer. The app will still remain on your phone (7 days if a free account…a year or more if you maintain a paid developer account) even after your clear your Apple ID from their Mac.

      And technically there are third-party BG (non-dexcom) apps that have the reset feature built into the apps now (like spike and xdrip+). I don’t use those though because I much prefer Dexcom’s app and algorithm for how it processes the raw data, calibrations, and outliers…but that’s a different subject. And I’m not intending to write guides on those apps, as I don’t use them myself. But, they are out there.

  6. In my case I had to do an additional step of selecting Product->Scheme->ResetTransmitter to get the build/install process to work.

    1. that is shown on one of the screenshots, you just must have missed that step. Others have missed it too. 😉 I’ll revise the post to try to emphasize that step so people don’t miss it. Thanks

    1. G4 transmitters don’t have an artificial cutoff like the G5 transmitters do…the G4 transmitters already go until the battery dies a natural death. So, you don’t need this for G4.

  7. Thank you so much! It worked perfectly and will hold me over until I get my G6 next week. What a relief! This is fantastic of you 🙂
    Thanks again!

  8. How would those of us WITHOUT ANY APPLE products be able to accomplish the same thing???

    The Dexcom Transmitter FORCED SHUT-DOWN is the #1 reason I stayed with my Dexcom G4…

    Well, that and my tSlim G4 pump isn’t G5 compatible…

    But when Tandem released their X2 pump and offered an “upgrade” option, I didn’t DOWNGRADE to X2 because Dexcom G5 wasn’t yet released and Tandem’s X2 pump wasn’t compatible with Dexcom G4!!!

    1. You’d have to look at android solutions…i’m not super familiar with those options. You could try x-drip+

  9. So I’m trying to follow your instructions (which are SUPER helpful btw!!!) but for some reason even though my iphone is plugged into my computer, it won’t create a provisioning profile for me to do the signing with, any tips? thanks so much for making this btw!!!!

    1. Did you add your apple ID account to the Xcode preferences? That’s how a provisioning profile is created for a signing team…first you have to create a developer account by adding one in Xcode preferences.

      1. I did and it comes up as my name followed by (personal team), but then it says there is no devices registered and failed to create a provisioning profile

        1. Ah, and there is a button beneath the “no devices registered” button that will allow you to register your phone. Look for the “Register Device” button in the signing team/provisioning profile area.

  10. First, thank you from the bottom of my heart for developing this app and sharing it. It has been a life saver. Second, it took me two downloads of Xcode on 2 seperate computers and 3 trys before I got it right. I think it had a little to do with the directions not sequencing well. Very minor things like FIRST delete all Dex apps from phone and computer, etc. Anyway, they were clear enough for me to get it after a small amount of frustration. Again, thank you and bless you.

    1. But, you don’t have to delete the dexcom apps from phone or computer. 😉 Depending on the computer you have, true…some older ones can’t be upgraded to the newer macOS software (High Sierra) in order to build this…so some people may have to borrow a friend’s newer mac. And, getting the transmitter’s bt pairing to leave Dexcom app is very much a step-by-step process (I did write them up in here)…but deleting the dexcom apps just allows you to be a little quicker with the unpairing…but deleting dexcom apps doesn’t need to be done. Just an FYI. Regardless, glad to hear you had success!

  11. Hello,
    Can I pay someone to restart my son’s G5 transmitter? Yes, I know you’ve given a very nice DIY set of instructions, but I’m not confident I can do it correctly. Can I send you or someone a G5 transmitter with a replaced batter (done by Tech Guruz) and get back from you a transmitter that will work again? If so, how much $ ?

  12. Thanks! All worked as expected! For me it took extra 10 minutes to figure out that bluetooth on iphone was off and that’s why it wasn’t looking for transmitter, but after that – all worked great!

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