Altimeter problems

FYI - I just received my replacement 970 and everything is perfect. 100% was hardware, and your description is pretty much exactly what I experienced too (manual calibrate, start GPS, elevation LEAP).

I'm beginning to suspect that Garmin may have received a batch of faulty sensors, as it seems a lot of the early purchases were affected by this, but more recent models (including those sent out as warranty replacements) are all fine. Also wonder if it's limited to region? My first was from USA (on holidays early June) but replacement is Europe model (back home, mid July, definitely a newer batch since they've been out of stock a few times since start of June, huge demand!)

Just had a reply from Garmin support, after 2 weeks, with the answer that, "they are aware of the problem and should be resolved with the next sw update". Hopefully this is the case. I will future update in this thread.

What was the text of your support issue?

Would you mind posting here? So I can see how close it is to my issues please.

Text? You mean the emails I sent?

Half the time I actually called them

But in email I just listed my observations and my troubleshooting steps and the outcomes, and based on that they confirmed that my issue was hardware.

High level what I experienced and sent to Garmin Support:

Issues started from the first run, watch a few hours old
Calibrate the altimeter: all good
Start run: elevation shoots up from sea level to 3200m then settles down around 3000m for a fairly flat profile, even though my profile was more an M shape going from sea level up to 85m max
Power fluctuated between 0W and 3990W, where my average runs are 250W to maybe 450W
Temperature flucated between -273C and +199C (clearly not possible since that would've k****d me!)
Similar results on all subsequent runs even with constant re-callibration
Elevation history on the watch gets 'lost' after a run
I tried with phone connected and disconnected
I tried rebooting watch
I tried removing/readding watch to GC via app
I tried turning bluetooth off/on and rebooting phone (just in case phone interference was a thing)
I ran with and without phone (again to rule out interference)
I did a soft reset of watch
I did a full hard factory reset and manually reconfigured everything
End result: same erratic behaviour from altimeter, power meter, and temperature sensor

Garmin Support asked me to share a few activities where I was experiencing the issue and where I was not. Since these were all routes I'd run before, some frequently, I shared the activities from my 970 (bad elevation) and my 955 (correct elevation). For my first run, I had actually done the exact route the day before with my 955 (on holidays, ran the route, next morning found 970 in store and bought it, ran same exact route that evening, before flying home next day)

After all this, they agreed that it was most likely a hardware issue with the sensors. I was not asked for any additional troubleshooting as I'd covered it all already. They opened a warranty replacement transaction and sent me a shipping label (since I bought the watch from a store, refund was not an option, but fully covered under warranty for replacement)

Here's my post on this forum that I started before I contacted Garmin. It contains screenshots and photos, details, my ups and downs: forums.garmin.com/.../elevation-issues

Thanks, I was more talking about what Huz_BE was referring to. The problem that will be resolved in software.

I do think it's weird that garmin replies to you as it is a hardware problem and now replies to me saying it's a software problem. I did see a picture in the 965 forum of someone having the altimeter shooting up to the galaxy and back. I had the same thing happen to me in a couple of runs. So that appearing on the 965 might suggest a software problem beyond the 970 alone. I also did encounter altimeter issues with my 955 and 965 (but nowhere near as wild as what I am getting with the 970). Then bought the 970 hoping all my troubles would be over...

One of the reasons that I moved from a 955 to the 970 was I wanted a reasonably working Altimeter.

Maybe it was a software problem all along, but when I contacted them start of June, they hadn't yet identified the root cause? All the signs suggest hardware on the surface, and end users can't perform any hardware diagnostics on these devices so Garmin would need to have a number of returns to test. I sent mine in without wiping it (just cleared my passcode and wallet) so that they'd be able to exactly replicate my actions for diagnostic purposes.

From what I've seen on various forums, a number of people have experienced almost identical issues to me and you, many seemingly early adopters like me (bought mine very start of June in a store, so likely was from one of the very first batches shipped out from Garmin in late May). My guess is that, by now, they have a good few of these devices returned, and have been testing them, and may since have tracked down the issue to software instead of hardware as was initially suspected .

The fact that they are now calling it a software problem makes this seem likely. Which will be good for customers - no need to send in the watch and wait for replacement (took me 2 weeks because they'd sold out yet again and had to wait for the newest batch off production lines, lucky I had my trusty 955 to keep me going). Just download the software (worst case do a reset alongside) and good to go!

Ironically I was back to my 955 for 2 weeks (while waiting for replacement 970 to ship) and it's altimeter was (and still is) 100% perfect! Had it nearly 3 years and zero issues! I upgraded for all the new features but I still love my 955 and do still have it. Old faithful!