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9.33/9.36 has ruined heart rate monitoring!


After upgrading my my fenix 7 to 9.33 I have noticed a few odd things about the heart rate that's displayed/recorded on my watch. Here's what I noticed:

First run with the new Firmware: My old H7 chest strap sensor, which worked fine before, showed sudden drops in HR of about 30 bpm while running at a constant pace. (H7 has a fresh battery.)

I thought was just the chest strap, but then I noticed sudden mayor changes in HR with the integrated HR sensor as well, when I was just at home. Within 2 seconds it jumped or dropped by about 20 bpm.

Also, when I stand up after sitting for a while, my heart rate does not change at all on the watch. It keeps showing mid to high 40s. However I can clearly feel that it's way off for about 15 to 20s and then it starts "catching up". > Again I big jump in HR on the watch. I tested this multiple times by comparing it to the data from my H7 + old watch where it behaved as expected – a gradual increase in HR.

I also restarted the watch which didn't help and I made sure I was wearing it correctly. (I wore it the same way before upgrading the firmware.)

Before the upgrade it felt very reliable and now I don't know what to think. Has anybody else noticed something similar? Any suggestions on what to do now?



  • I've also noticed similar issues since the latest update (e.g. the sudden drops in BPM). And I think this is closely related to the issue I posted here:

  • Guten Tag. Die Pulsverzögerung ist groß und es deutet darauf hin, wie es gelaufen ist. eine Verzögerung von mindestens 15 Sekunden. sprünge von 20-25 Schlägen während des Trainings .firmware 9.33

  • Unfortunately no. HR bug fix is not mentioned in change log whatsoever.

  • I am not sure, if every change is reported in the changelog

  • Important changes are mentioned in changelog.

    Additionally, garmin did not indicate whether it recognizes this problem, let alone trying to solve it.

  • I also have the feeling the HR sensor it less responsive since 9.33

  • I think that lots of people here are missing the point. The problem is NOT that WHR is inaccurate by-construction, or that it depends on how you wear the watch, how it locks on your cadence, etc. We already know these.

    The problem rather is that: WHR has become way worse since 9.33. We have been wearing our watch the same as before 9.33, we have been running the same as before 9.33, we have been sweating the same as before 9.33, BUT the only thing that changed since 9.33 is the WHR measurements which have become way worse (I am running like *** and gives me 90 BPM, whereas a month ago it gave me 170 BPM). And this happens with many people.

    This cannot be a coincidence, and Garmin, through Garmin- Chris, apparently admits that there might be an issue here.

    So, please, don't try to teach us how to properly wear our watches, how to properly wear a chest-HRM, etc. This is not the point.

  • I don't think anyone was teaching... rather asking / double-checking. ;)

    But yeah! This is the point. It changed with 9.33. Unfortunately it's relatively hard to show a before and after here. I for one don't have two F7 lying around with 8.37 and 9.33.

    However I think the measurement is now SO wrong, that it's actually obvious without comparison altogether.

  • I for one don't have two F7 lying around with 8.37 and 9.33

    What do you need to see?

    Assuming we are still talking about external HRMs I could test with 3, all on different firmware with 9 back to 7

    I have not been able to reproduce the issue with external HRMs (I don't use optical though) as I have said before though (Polar H10, HRM Pro)