Is there a hardware difference in Tandem t:sim x2 versions for BIQ versus preloaded CIQ?

For t:slim x2 pumps that are:
i) preloaded with BIQ algorithm and eligible for the CIQ upgrade; versus ii) preloaded out of the factory with the CIQ algorithm?

Since CIQ algorithm was FDA approved after BIQ, as development time progressed, the hardware that it runs on could theoretically be “new and improved”: better touch screen sensitivity, better battery life, less prone to loosing the USB cover port, etc., etc. ,?, ?..
Good design allows the CIQ algorithm to be backwards compatible to run on the initial ‘older’ BIQ hardware build.

As a reference, my Oct. 2020 t:slim x2 unit came with only BIQ, and has not yet been upgraded to CIQ. It currently (23Aug.2021) defines:

  • t:slim Software: Carlsbad v6.3
  • Pump model: 0010022717
  • PCBA Serial, Model: (i left this blank); 1002663.

Is an out of the factory CIQ pump enabled hardware, newer, better than BIQ enabled hardware? I would expect that the model types would be different. I am aware that once BIQ is upgraded to CIQ, there is no software roll back.
Maybe my question can only be answered by users that received an “out of the factory” CIQ enabled pump.

No, the hardware is exactly the same, barring any degradation in the used system, like how batteries decline over time and screens can change. If you ever get a warranty replacement pump, it might seem different but will be built to the original specifications. Any hardware upgrades require another FDA submission/approval cycle, which is an unnecessary expense when they already know what’s in their pipeline and were able to plan in advance for it. It just doesn’t make sense business-wise to go through all that unless they’re doing it to unveil a complete new model.

When the X2 was first approved it came super-loaded with extra hardware that it wasn’t using at the time, in anticipation of future upgrades that would use it. For example, there were 2 separate Bluetooth radios that had no purpose whatsoever originally. The first one was finally put into use with the 2017 software upgrade that allowed Dexcom G5 integration, so your CGM data was displayed on the home page. The second Bluetooth radio was teased to have a purpose in late 2019 with the Control-IQ approval, with which came a mysterious new menu option to enable Bluetooth communication. It wasn’t until 2020 that we actually got to flip that switch, though, so the pump could talk to our cell phones and the T: connect app.

They’re not very forthcoming about the extra bits and pieces, so who knows what else may be hiding under the surface.

Edit:. I do think we can expect a T:slim X3 in the near future, as the X2 could afford hardware upgrades, but I’ve never actually heard any mention of such. Newer Bluetooth and other communication hardware, USB-C (which could significantly reduce the overall size, too) or wireless charging instead of the annoying micro-usb, smaller screen (I don’t think they’ll get rid of it altogether as a T:sport alternative) as they focus more on mobile control, maybe pump mechanism changes to reduce pressurization and allow FIASP/Apidra use, etc…


I got CIQ directly, in June 2020.
My info is similar to yours, except software is Moonlight v7.3.1

Did you intentionally choose BIQ instead of CIQ, if so why?

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BIQ was the only option available to me in Oct.2020 (Canadian market). The CIQ upgrade is now available, but I have not made the upgrade.

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EXCELLENT, technically complete answer, thank you so much!

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Just to add a datapoint from an older t:Slim X2. This pump goes out of warranty at the end of September so I think that means I got it in Sept 2017.

I may have used it with a G5, but certainly used it with a vanilla non-feedback G6, then the B-IQ upgrade, followed by the C-IQ upgrade and then the minor C-IQ 7.4 update that, I think, mostly cleans up the look of a few screens for better consistency.

While I don’t know how to interpret either the pump model or the PCBA model, mine are:

Pump model: 001000096
PCBA model; 1000153

And I am running Moonlight V7.4 software.

Stay safe!


I have the older version. Do you know what changed in 7.4?


I’m afraid that I don’t know specifically what changed, but here is my best recollection:

  1. I believe that NOTHING changed in terms of the C-IQ algorithm or parameters.

  2. I think that the changes were purely cosmetic: maybe some reorganization of the look of a few of the confirmation pages such as substituting a green check for an “OK”.

I am on the road with only a phone, so don’t know if I could do a better job of finding the differences between 7.3 and 7.4 if I had a laptop.

Here is what I might suggest that may be better than my often-poor recollection:

  1. Call Tandem tech support to see what they say or if they can provide some sort of 7.3 vs 7.4 document.

  2. Login to I expect that you may be eligible for a new “activity” that is the upgrade to 7.4. I believe that you will find that you can start that training … but not necessarily complete it … without the need for a new prescription or note from your endo. In fact, the very fact that you can start that training without prior approval, tells me that there are no changes “of substance” between 7.3 and 7.4.

I apologize that I do not have a more definitive answer for you. I’m hopeful that another member of this community who hAs either upgraded from 7.3 to 7.4 more recently than I or has a better memory than I can better describe the differences.

Good luck.


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Absolutely nothing significant. They rearranged the menu items a little bit, I think there’s was more switching over to non-verbal confirmation screens (more X’s and ✓s instead of words), and added a max basal setting. If I remember correctly, the max basal doesn’t even apply to Control-IQ, it limits what you can program in the basal profiles and how much a temporary basal rate can deliver.

You can login to the portal and get it if you want, but it’s not worth much hassle. This one doesn’t require a new prescription, but I think there were a few training modules you have to watch, which was largely a repeat of Control-Iq training.


I might do it just to learn the process, when I have some spare time.