# Guardian 4 Sensor Updating Immediatley after Warm Up
**URL:** https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892
**Category:** Type 1 & LADA
**Tags:** cgm
**Created:** [February 25, 2026, 1:13am UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892 "2026-02-25T01:13:29Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@GSalge](https://forum.fudiabetes.org/u/GSalge)
#### Post date: [February 25, 2026, 1:13am UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892/1 "2026-02-25T01:13:29Z")
I have the 780G pump and Guardian 4 sensors. The majority of the time, I have no issues. I just started a new batch, and so far, 3 have failed. The last two have begun updating as soon as the warm-up is complete. I can only alternate back-of-arm sites back-to-back so much without looking like I have been in a fight. Has anyone just gotten a bad batch/box? I am switching to a new box tonight.
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### Author:  [@LJAZ](https://forum.fudiabetes.org/u/LJAZ)
#### Post date: [February 25, 2026, 12:48pm UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892/2 "2026-02-25T12:48:00Z")
I have had that happen with the G4 sensors from time to time. I’ve found that if I just wait it eventually starts working normally. It can take another couple of hours before it sorts itself out which is annoying but given time it starts working as it should.
I don’t know about an entire box with the issue, but I have had a few in row go through that issue.
I don’t put them on the back of my arm either. I find that impossible on my own. I just put them on my abdomen and they work perfectly fine. Talked to my endo about doing that and he said it won’t make any difference. I do a fingerstick usually once a day and the results are pretty close,
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### Author:  [@GSalge](https://forum.fudiabetes.org/u/GSalge)
#### Post date: [February 26, 2026, 1:14am UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892/3 "2026-02-26T01:14:26Z")
Thanks for the reply. I have tried waiting it out. These last 3 have not given 1 reading. I usually change mine out at night with help. I waited overnight and after work, and still no readings. The Medtronic representative who trained me had me insert it on my outer thigh. I normally use my arm and did so for the ones that did not work. I do use my thigh when I don’t have help. I finally switched to a new box, and all is good again.
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### Author:  [@LJAZ](https://forum.fudiabetes.org/u/LJAZ)
#### Post date: [February 26, 2026, 12:27pm UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892/4 "2026-02-26T12:27:41Z")
Wow, waiting overnight and still no reading seems something is really wrong. I’ve never gone more than about 2 hours. I assume you know that Medtronic will replace the failed sensors for free.
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### Author:  [@GSalge](https://forum.fudiabetes.org/u/GSalge)
#### Post date: [March 4, 2026, 1:21am UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892/5 "2026-03-04T01:21:26Z")
Yes, I request replacements each time. It is stressful and a pain to have to insert and tape up.
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### Author:  [@ChrisH](https://forum.fudiabetes.org/u/ChrisH)
#### Post date: [March 10, 2026, 3:35pm UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892/6 "2026-03-10T15:35:07Z")
The Guardian 4 takes time to update. I once had to wait approx 36 hours but was ‘on manual’ testing strips until the pump was in full operation. As time goes on, you should see updates taking less time.
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### Author:  [@TomH](https://forum.fudiabetes.org/u/TomH)
#### Post date: [March 11, 2026, 12:52pm UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892/7 "2026-03-11T12:52:56Z")
I’m not a Guardian 4 user and may not understand the process or requirements for an update. However, neither will I be tempted to try it or their pump if this is the norm. Are other people experiencing the same time frame for a relatively simple firmware update? Perhaps your connection was interrupted routinely or you were on an abominably slow connection? Even with those events, taking more than a few minutes to accomplish an update is unacceptable. Have you reported the issue to the company? Any response? I’m not blaming @ChrisH, but the time frame is ridiculous; hopefully there’s more to the story.
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### Author:  [@ChrisH](https://forum.fudiabetes.org/u/ChrisH)
#### Post date: [March 11, 2026, 3:01pm UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892/8 "2026-03-11T15:01:59Z")
When I spoke to my Dr at the time, she said that the insulin pump/guardian 4 had to calibrate first, for it to be accurate. This is for basal amounts specifically because the guardian 4 does not use inputted basal configuration and ‘reads’ your BG levels over a certain amount of time to determine the basal amount (based on historic data). Hope that the info helps. Else just google it. There are plenty of information on Medtronics website about the guardian4.
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### Author:  [@LJAZ](https://forum.fudiabetes.org/u/LJAZ)
#### Post date: [March 12, 2026, 1:16pm UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892/9 "2026-03-12T13:16:55Z")
The normal process for starting a new Guardian 4 sensor is that once it’s inserted and the transmitter is attached the pump will recognize a new sensor. At that point it starts a 2 hr warm up cycle. After 2 hrs the pump alarms for you to input a fingerstick value for calibration and then it’s off and running. But sometimes at the end of 2 hrs you get an error that doesn’t call for a fingerstick but says the sensor is updating. Eventually it will finish the ‘sensor update’ (I have no idea what that is) and finally call for the fingerstick value to calibrate. For me, this has only happened occasionally and takes as short as 15 minutes or as long as another 2 hrs. The sensor update is not normal and happens only occasionally.
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### Author:  [@TomH](https://forum.fudiabetes.org/u/TomH)
#### Post date: [March 12, 2026, 1:40pm UTC](https://forum.fudiabetes.org/t/guardian-4-sensor-updating-immediatley-after-warm-up/15892/10 "2026-03-12T13:40:48Z")
@LJAZ Thanks for the explanation! Glad it doesn’t impact people regularly! That said, it seems similar to what my past experience, though greatly improved over the past several months, says about the Dexcom G6 and 7: it happens just enough to make you question the sensor. Seems we all have our crosses to bear!