How to fix Apple Watch heart rate monitor not working

fix Apple Watch heart rate monitor
Figure 1 — no measurements at start and middle!

Fix Apple Watch heart rate monitor!

About six months ago I noticed that my Apple Watch wasn’t consistently reading my heart rate during running workouts. The watch started displaying “measuring” my heart beat for minutes (see Figure 1), especially at the beginning of a run. Sometimes the heart rate monitor stopped working to such an extent that I couldn’t even get a few readings during a 25-minute run (see Figure 2). I love my Apple Watch but it was time to fix my Apple Watch heart rate monitor.

Figure 2 – no heart rate chart!

After doing some research, here’s what I’ve curated from various internet sources, summarized in one convenient place.

The first thing to determine is whether your watch’s heart rate monitor is working at all!

If your Watch completely stops reading heart rate during workouts

Check the following settings on your watch.

—On your iPhone, go to Settings > Privacy > Motion & Fitness and check that both Fitness Tracking and Health are On.

—Open your iPhone’s Watch app and:

  • Go to General and make sure that Workout Power Saving Mode is Off.
  • Next, go to Privacy and check that both Heart Rate and Fitness Tracking are both On.
  • Finally, go to Passcode and check that Wrist Detection is On.

If any of these settings are incorrect, they will prevent your watch from reading your heart rate during a workout. Set them correctly, and test your watch again.

If your Watch is flaky reading heart rate during workouts

—Clean the sensors on the back. The two that read your heart rate during exercise are the white LEDs at 3 and 9 o’clock that you may have noticed flashing green from time to time.

—Make sure that the watch is snug on your wrist.

—Apple says that cold weather conditions can make reading your heart rate less reliable. If the flakiness of your heart rate monitor seems to be worse on cold days, try wearing warmer clothing on the arm where it’s fastened.

—If your heart rate monitor is still flaky, try the approved Apple resetting options listed here.

One workaround to try

[Updated on April 16, 2020] While running today I thought of a workaround that I believe is worth trying.

When you’re not running the Activity app, an Apple Watch only reads your heartbeat every ten minutes. One possibility is that — due to unknown circumstances —  during the first few minutes of your exercise, your heart rate is changing too fast for the watch to accurately measure it. Since the watch’s Heart Rate app turns on the constant heart rate monitor, try the following:

Before you start your exercise routine, select the Heart Rate app and wait until it shows you your heart rate before starting the Activity app and your exercise.

Since my watch is now OK I can’t test this, but perhaps it will work for you. Please share your experience in the comments.

What to do when none of the above helps

I tried all of the suggestions above. However, I was skeptical that any of them would work, because I’d seen a slow degeneration in the reliability of my watch to read my heartbeat while using my watch for the same workout over the same route for months.

I concluded that my watch heart rate sensor was defective. Luckily my Apple Watch Series 3 was still covered by AppleCare. I took it in to our local Apple Premium Service Provider. As I expected, defective Apple Watches are returned to Apple for repair or replacement. Before sending it back, I unpaired the Watch from my iPhone (important!), which backs up the Watch contents to the phone.

After a week turnaround, Apple sent back a new replacement watch. It was a little strange not wearing a watch for a week, and it was interesting to see the limited workout data provided by my iPhone compared to what I was used to from my watch.

I’m happy to report that the replacement watch now works perfectly during my workout. Figure 3 shows the continuous heart rate chart shown by the new watch. And Figure 4 compares typical charts from the old and new watch.

Figure 3 – the replacement watch
fix Apple Watch heart rate monitor
Figure 4 – comparing typical old and new Apple Watch heart rate charts

Conclusion

Many people have reported that the heart rate sensors on an Apple Watch have become unreliable. Unfortunately it seems that the watch heart rate sensors can degrade over time, and the various “fixes” suggested online might not always be successful. I was lucky that AppleCare still covered my watch. I don’t know what Apple would charge for an out-of-warranty fix or replacement. If you don’t have warranty coverage, I suggest politely pointing out that this defect seems to be widespread, and asking whether Apple will replace your watch anyway. Good luck!

Please feel free to share any other fixes, suggestions, or experiences with this problem you’d like to add in the comments below!

16 thoughts on “How to fix Apple Watch heart rate monitor not working

  1. Thanks for sharing your experience. My watch is getting close to a year old and the heart rate tracking seems to be degrading too. I’ll go in before my apple care expires and get it replaced.

  2. Please see the new section I’ve just added “One workaround to try” (April 16, 2020) for a procedure that may help. If you get the chance to try it out, please share your experience!

  3. I’m a Biomed (I repair medical equipment) and I would be very surprised to learn the sensors degrade over time. The Apple Watch uses light sensors and an algorithm to measure your HR, in 20 years, I have never seen any of these types of sensors with a limited lifespan. Typical causes of failure are physical damage to the sensor or wiring. Either Apple has an unusual issue with their hardware degrading over time or something else is causing this issue.

    Thanks for posting this though, my fiance is having the same issue and I was looking for some btdt from people. Going to try some of the other things you suggested.

    1. Yes, the issue surprised me too, and I wish I had a definite answer. But the replacement Apple Watch fixed the problem (at least until now) for me, which is evidence that some kind of hardware problem may be involved.

  4. I had this same problem. My heart rate was routinely displayed on my watch in all situations except while running. I finally determined that my link type band was too loose when running. Apparently it did not make consistent enough contact with my wrist as it flopped around a bit while running. I did not want to take another link out because then it would be too tight. I wedged a piece of foam under latching part of the watch band which snugged up the back of the watch to my wrist. This solved the problem. I only use that while running.

  5. Thanks for posting. Wish I came across this sooner. And also should have taken my watch to Apple before my Apple care expired. My watch does this and also pulls random readings that can’t be correct: goes from 88 to 160 to 53 to 88 within minutes. There’s no way I’d be functioning normally with that kind of HR variation.

  6. Why would my heart rate reflect in yoga but not in outdoor walk / run ? It’s very frustrating – Watch is not even six weeks old – I’ve done all the upgrades de link re link as directed by the Apple store but it still does not work

  7. A superbly documented summary ! My series 4 running workout record looks just like your OLD watch image. The workout chart is much better during stationary bike workouts, in which I note there is little arm movement.

  8. Hi,

    this is important!
    I thought my watch heart rate monitor was not working well, but then I decided to use a nylon band which you can adjust precisely on your hand.
    in addition make sure the watch is about one inch from your wrist.
    now it’s working fine fo me!

  9. So this issue ONLY occurs while running for me. If I do crossfit (which supposedly is a hard exercise to capture HR on) or cycling, the watch is flawless and never loses monitoring! Running, it SUCKS! It can barely keep a measurement even when I start the HR App first. It has something to do with the swinging of the arms, that throws it off and yes, the watch is snug and does not move around. Its very frustrating.

    1. Mike, I agree it probably has something to do with arm movement, since I, like you, never see the issue during other exercise routines where my arms don’t move as much. I am still seeing the problem while running, even with my new watch, but it’s so inconsistent from day to day. I suspect, as other commenters has mentioned, it’s related to the precise positioning of the watch on the wrist and the tightness of the strap. But, despite filling around, I haven’t found a way to reliably avoid the issue.

  10. Thanks for all the comments about not reading heart rates during work outs. I have all the setting turned on described above in the this chat. I am on my 2nd series 5 watch in 4 weeks. Sometimes I do get a reading. I run with both a fit bit charge and the apple watch. The fit bit always gives me a reading. The fitbit routinely shows 160 BPM during my runs. A year ago I ran with a 12 lead holder heat monitor and it agreed with the fit bit. Today I ran 1 mile 9 minutes and the watch stop reading 30 second in the run at 79 BPM. The times I did get it to read was a slow increase in my pace. slowing down when it stoped recording then speeding up. Finally got it to read 140 bpm for 30 minutes. I am doing a 10 mile run tomorrow and hope a tighter wrist band will help. However it sounds like fast changes in heart rate cause the watch to stop recording. All the apple store say is that is strange and gave me a new watch. It is nice to know that many people are having the problem.

    1. Tom, you mention another possibility: that the Apple Watch simply doesn’t handle rapid changes in heartbeat well. That may be what’s happening to me too. Hearing that other heartbeat monitors don’t have this problem implies that Apple’s tech is, perhaps, inferior.

  11. Adrian,
    I Got the watch to track heart rate for this morning’s 10 mile run by tightening the wrist band one notch and positioned a little closer to my elbow but still on my wrist. Heart rate was mostly 140 bpm with one spike to 177 bpm. It drifted up to 160 bpm at the end of the run. The Fitbit was 140 bpm for first 2 miles then jumped up to 165 bpm for the rest of the run.

    The GPS pace from the apple watch seemed to vary faster and slower than my actual pace on hills. 8-12 minutes per mile for apple watch and 8 min 30 sec to 9min and 40 sec for the Fitbit.

    I could not cut and past any of the graphs from iPhone or Fitbit app into this comment. How do you do that?
    regards. Tom

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