Beware Garmin customers that own, or are thinking about buying, any of the products containing the optical heart rate sensor.  I have now owned three Garmin products with the wrist-style sensor (Vivoactive HR, 735xt and the 935xt).  All of the devices displayed some level of this plastic warping defect.  Here is a picture of my older 735 with the defect.

The first watch I owned with an optical HR sensor was the Vivoactive HR.  After about six months it started to warp.  A month later the sensor failed to be able to read an accurate HR.  At the time I thought I must have dropped it or damaged it during use.  I then purchased the 735xt as both an upgrade and fix.

After three months with the 735, I noticed the issue with the new watch.  I watched over the course of the next 30 days as the warping got worse, to the point the sensor stopped reading.

Here is the biggest issue for Garmin consumers.  When I contacted them, they advised that the watch is only covered under a 90-day warranty.  I was about two week outside of that window.  I would have had to have paid $150 to obtain a new refurbished unit.

So, I then bought a 935, thinking the more sunk-in design of the sensor would fix the problem.  I purchased the 935 at the end of September 2017.  Today, at the end of March 2018, the watch is demonstrating the same sensor warping issued the other two watches did.  Here is what it looks like:

Garmin Forerunner 935xt with optical HR sensor warping.

I’ve again contacted Garmin about the problem on the third watch.  I was again told this issue is only covered under the limited 90-day warranty.

I’ve used each of the three watches as my everyday watch.  They are on my wrist 18 hours a day, 7 days per week.  Many times I wear the watch throughout the night as well.

I have no problem with this being an issue if Garmin would stand by their products.  I’m sure I am not the first person to experience this.   After three watches, all having the same issue, I’m confident it’s a design/cheap materials issue that Garmin is aware of but refusing to do right by their customers.

I love the functionality of Garmin products.  I’ve owned almost every Garmin GPS watch starting around 2000 with the old Forerunner 205 (I think that’s what it was). I must agree that Amcrest gps tracker is the best but Gramin is the close second. I’ll fight with the company a little more, but if they decide to not stand by their product and replace this watch I’m done and will look to move over to Polar or Suunto.

I would love to hear if others have experienced this issue as well.



  1. Yes!

    I’m on my sixth garmin 935 under UK warranty. I had to argue to get the watch four and five, watch six was automatically replaced using a webpage on the Garmin website due to the barometer-altimeter-compass failing after contact with water. The ABC fails of the sensor (underneath) contacts water more than a few times during swimming.

    These two things are the main defects for this watch. It’s defined for doing triathlons but obviously can’t really withstand regular swimming, even in fresh unsalted water. You get altimeter drift over time with such use when out of the water and eventually it’ll drift so much as to be useless.

    As for he heart rate sensor housing cracking, it’s happened on all 935 watches for me. I’ve seen friends have it occur on the 945 too and 935XT. This doesn’t happen with the Apple Watch or other manufacturers and is therefore obvious that Garmin aren’t designing, engineering or manufacturing their watches to a high enough standard to resist such a basic failing as using cheap plastic on a heart rate sensor!

    At least they’ve replaced the watch every time for free since 2017, for me in the UK.

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