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Serious problems with Garmin Fenix 6X Pro wrist HR sensor and altitude sensor

mika.rissa
over 4 years ago

Does anyone have positive experiences of accuracy of Garmin Fenix 6 sport watches? 

I have noticed a growing inaccuracy in a built-in wrist heart rate sensor of my five months old Garmin Fenix 6X Pro watch. I checked the accuracy of the wrist HR sensor on a first run with the Fenix 6X against a Garmin HR belt and the values were almost identical. I checked the Fenix 6X HR wrist sensor again today on an easy recovery run and it turned out the wrist HR values are pretty much useless now. 

See the HR sensor data in the chart. The red values are from the built-in wrist sensor of the Garmin Fenix 6X Pro device. The green values are from the Garmin HR belt captured by an old Garmin Fenix 5X device.

The wrist sensor of the Fenix 6X Pro gives on average 9% higher values than the HR belt. The highest error is +29%. At the highest error point the Garmin wrist sensor appears to give random high values for several minutes. There is nothing on the rather flat downwards trail that would explain why the measured HR got so high at that point for several minutes.

Also the built-in barometric pressure sensor of the Garmin Fenix 6X Pro appears to be surprisingly inaccurate. I entered manually the right starting altitude to both devices before the 47 minutes test session. The old Fenix 5X provided very accurate figures throughout the session. The new Fenix 6X Pro developed an error of +3% within 47 minutes. The error in the Fenix 6X appears to grow by time. How an earth is this possible? Garmin doesn't test the products before shipping them to customers?

I think Garmin should stop selling these pro-consumer devices until they can fix the quality of their sensors. The Garmin Fenix 6X Pro includes their "latest generation" wrist HR sensor, so I guess this is the best they can do. I know several people who base their training plans and recovery periods on data coming from their Garmin Fenix 6 devices. This is seriously bad with this quality of data. Also the altitude error is a serious problem in the mountains if one needs to call rescue.

I'll send the device to Garmin for a warranty replacement today. This is now the third time I need to get a Garmin Fenix device replaced after the quality of the wrist HR sensor data has gone bad without explanations.

Luckily I have my old Fenix 5X as a backup. It also has a poor wrist HR sensor and Garmin didn't replace it third time after warranty period ended, so I purchased the new 6X that now goes back. But the poor HR sensor quality doesn't really matter in running as I've moved to power-based running training because of the inaccuracy of the wrist-based HR measurements. However, it would still be nice to get a properly working Garmin device to capture training effort in activities that power-footpods can't capture.

Is my Fenix 6X Pro the only poor unit there, or is the serious inaccuracy a common problem in Fenix 6 units?

  • 0 over 4 years ago

    Garmin support reference ID 16205334K0 in case someone from Garmin product management wants to check the case

  • 0 over 4 years ago

    I sadly have a similar situation with my Fenix 6X pro too... 

  • 0 over 4 years ago

    All is working acceptably with WHR in an activity, on my F6X Pro Solar (and MARQ) on SW 8.73 beta. More detail (charts and activity links) in my recent post on the MARQ forum here https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/marq-series/219127/heart-rate-sensor-show-very-high-result/1042959#1042959

    Elevation plot seems fine too (please note the y axis scale) as the activity started/finished at the same spot.


    [Addendum - I've put the effort in to making the posts I have, so that folks can see that WHR and elevation tracking does work fine for many of us (so it's not universally broken).  If you keep seeing the issues with diverging/drifting elevation or poor WHR, do try the latest beta software and email in your observations to the Odsweng folks. Ultimately though, it could be a hardware fault with your particular watch, with your only course to resolution being through Garmin customer support for a potential replacement watch.]

  • 0 over 4 years ago

    I have problems with HR too on my fenix 6pro. I hope they take this problems siriously and fux this asap

  • 0 over 4 years ago

    There does seem to be lots of threads on this topic. Conversely lots of people say it’s fine for them, so who knows. 

    All I know is this: https://imgur.com/a/IYef1q7

    Huge discrepancies between the super accurate Apple Watch 4 sensor on a tempo run. At one point the difference is 44bpm. It’s worthless data at that point. 

  • 0 over 4 years ago in reply to NotHappyJan

    I'm assuming you don't know which watch is correct (if either), as you don't have chest strap data to compare against.  Looking at the 'super accurate' Apple Watch 4 graph, the HR climbs to over 190 bpm for the last few minutes. Working on the estimated max HR (and I know it can vary for some) of 220 minus age, and assuming that you're over 20 years old, that means the Apple Watch 4 has you at near max HR for most the run (well over max HR if you are 40 years+). There's also a suspiciously straight ramp up of the AW4 HR graph in the first 1:40 of the activity.  The 150-165 bpm of the Fenix 6X PS is arguably more believable if you're over 30 years old.  In the end, who knows what is right without a chest strap HR to compare against; but I suggest it would be worth doing that test at some point, so you know which watch's WHR is working better for you.  (Alternatively, if accuracy is important to you, all the main manufacturers (Garmin, Suunto and Polar) will advise you to use a HR chest strap anyway - but I'm not going to suggest that's an excuse for WHR giving numbers that are a work of fiction.)

  • 0 over 4 years ago in reply to Crispin_Ellisdon

    Apple Watch 4 and above has the best optical wrist based sensor in the business, it’s got a totally different design than any other manufacturer. Do a little bit of research and you’ll see what I’m talking about. DC Rainmakers AW4 review, the HR accuracy section is a good start. By the way Apple implemented ECG in AW4 and above and when they did that, they had to redesign the optical wrist based sensor.

    As for the results, I’m under 30, but I’m not SUPER fit. This run I pushed myself pretty hard, and I was almost breathless throughout. There was absolutely no way I was at 150bpm. Further to that, I crossed checked with a manual reading at the end and I got 180bpm, obviously slightly lower since some time had passed since I stopped running. 

  • 0 over 4 years ago in reply to NotHappyJan

    NotHappyJan, you had your own HR thread, where I said Garmin guys never acknowledge HR problems. To my surprise, this time one of them stepped in, kind of acknowledged the problem (but for hike activity only), then locked the thread (presumably, to drown it down the pages) and sent you a personal message. Did anything good come out of it?

  • 0 over 4 years ago

    Comparison of WHR and HRM-Tri while riding on an indoor cycling trainer this afternoon. Had one of the watches transmitting WHR to another watch on the handlebars. Pretty damn close overall.

  • 0 over 4 years ago in reply to philipshambrook

    Philip, I would give anything to have that kind of accuracy from the WHR on an indoor trainer. Mine rarely gets above 120 bpm while I am easily sitting around 160 bpm.