External heart rate monitor no longer tracks on Apple Watch

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External heart rate monitor no longer tracks on Apple Watch

For years, historically I’ve used a third party heart rate sensor on chest of forearm. They are much more accurate when doing things like weight lifting or heavy running, hiking.

they pair find via BT with the AW Ultra 2 (I’ve used them since oh AW 4/5). historically they are the primary HR sensor, and the HR sensor in the watch is dark - so not sensing.

Now, since either ios 18.x or watch OS 11, they seem to be paired, but the watch continues to have the sensor active AND the external HR sensor does NOT seem to be the primary or even tracked at all?

Does anyone else see this? Is this a bug, or a new feature - that deprecates the availability.

One additional advantage historically was that by turning off essentially the onboard HR sensor while an external was used, meant some battery savings. That too seems to have been lost.

[Re-Titled by Moderator]

Posted on Mar 7, 2025 06:33 AM

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Answer 1

Apr 21, 2025 07:55 AM in response to Paulmerc

Same issue here; very frustrating. I tried to re-order data sources, tried to pair and unpair multiple times. Tried different HRM units. Tried a complete reset of applewatch SE2. Tried to delete/reinstall Workout app. Tried enabling/disabling low power mode. No positive results.

Workout app and applewatch persist to use the onboard HRM.

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Answer 2

Paulmerc Author

Level 1

12 points

Apr 21, 2025 08:24 AM in response to Paulmerc

Yes, I’ve tried all those things.. I contacted the compan, Scosche in this case and they said it is most likely an issue with the AWU/2 and obviously the os/wos, which I find hard to believe.. I’ve updated to 18.4/11.4 at this point and it’s possibly BETTER, but still not fixed. Still has the onboard active and still often loses connectivity with the external and then nothing. A pause and restart sometimes works for a while, as does trying to confirm pairing AFTER starting a workout.

I think something might have to do with the fact that the Rhythm24+ that I use now essentially has TWO BT beacons, and this might be confusing the watch. Don’t know, and the company says that now that that model is disco’d, there won’t be FW updates or research on the issue.

What model external HR sensor are you using?

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Answer 3

Apr 21, 2025 09:58 AM in response to Paulmerc

Same as yours! Rhythm24+.

I tried to switch modes within the app (from Running to HR only), that didnt work either.

It was working perfect last year, so I think it’s a watch OS issue (because if it were ios, then youd have the same issue on your phone, which I dont when i use it with icardio, strava, zwift, etc.). I would agree that the capability of the Rhythm to report HR and cycling cadence is confusing watch OS, because i have seen it pair without the tire diameter/width, only to later on report the settings for it.

it’s a shame… the Rhythm 24+ is the only wearable sensor package anyone would ever need; surprised apple didnt buy/adopt their sensor package in the first place.

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External heart rate monitor no longer tracks on Apple Watch

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