Garmin Fenix 7 Heart Rate Monitoring bug after firmware 9.36

Fenix 7 users are reporting issues with heart rate monitoring after upgrading the firmware to version 9.36. Some users have confirmed that the issue started after implementing firmware version 9.33. The issue is being looked into by Garmin and it is being considered a bug.

Fenix 7 smartwatch

Fenix 7 firmware version 9.37 does not come with a fix for the heart rate monitoring issue. We expect a future rollout to address the functioning of the heart rate monitoring feature of the Fenix 7 watch.

Heart Rate Monitoring Issue Description on Fenix 7

Fenix 7 devices owners have reported the following issues with heart rate monitoring:

  • The heartbeats per minute fluctuate rapidly. It may show a drop of 30-40 bpm or show a remarkable increase of 30-50 bpm without any associated activity that would cause the heartbeat changes.
  • The watch continues to track heartbeat even though the chest strap is in another room and not in use. The data so calculated shows diverse fluctuations.
  • The data collected by the heart rate monitoring strap and Fenix 7 watches differ in respect of heart rate variability. The HRM strap-based sensor records the heart rate data in a natural progression in the middle of an activity. However, Fenix 7 seems to display heart rate changes in a delayed sequence. So, you will see vertical spikes and plateaus in heart rate data collected by the Fenix 7 watch.
  • To put in a summary, the Fenix 7 watch heart rate data does not match the HRM strap-based heart rate data.

This bug has been caused after the firmware versions 9.33 and 9.36 were rolled out. The earliest reports for the bug started appearing 2 months back.

Garmin is aware of the issue and is working on fixing the software to address this issue.

Here are the user feedback and reviews on this heart rate monitoring issue with Fenix 7 watches:

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.

Source – Garmin site

You can notice that the Fenix 7 device owner has confirmed that the watch seems to be showing a delayed response to physical activity when it comes to heart rate monitoring of the watch.

One Fenix 7 device owner has shared his review about the issue. The heart rate monitoring issue seems to have been spotted only after the firmware upgrade to 9.33 happened. Subsequent firmware updates did not resolve the issue.

My H7 worked totally fine with my Fenix 7 unitl I upgraded to 9.33. Then it showed data that made no sense at all. (HR dropped from 150 to 130 within 2s and I didn’t change pace at all.)

The point is that none of the issues were here before the upgrade.

The wrist heart rate sensor was even good enough to use it for running. But now…? If I adjust my pace to stay in an HR zone, I can’t tell if that did anything or not. It takes way too long to update.

From the user review given below, we can see that the heart rate monitoring suffers a lag when you are initiating or participating in strenuous activity.

That’s the problem. The issue will only reveal itself when you perform some explosive action such as HIIT which will raise your HR from Z2 to Z5 within about a 10-15 second window.

If you are experiencing issues with heart rate monitoring on Fenix 7 after deploying firmware 9.33 or 9.36 or 9.37, please do contact Garmin support and open a bug request. We understand that Garmin is already working on the bug resolution actively.