Major Altimeter-Barometer-Temperature Malfunction

Over the past several years, I have had a series of Forerunners (910XT, 920XT) and Fenixes (2, 3, 3HR, 5x) which have all developed total malfunction of altimeter-barometer-temperature. I seem to have been one of the few until the 3HR, on which many had similar problems. Just the other day I was thinking to myself that maybe this would not happen with the 5x, until mid-morning yesterday when suddenly while at work, the problem developed on my 5x. The clue is that the altitude suddenly went to approximately -65,000 feet. The barometric pressure showed no change. The temperature read 451 degrees. I tried recalibrating the altimeter, at which point the barometric pressure became bizarre and incompatible with life. So, I updated to the new beta firmware (4.21) with no change in these reading. I then soaked in soapy water (on the theory that the sensor port may be clogged; this has never worked for me). Then I did a hard reset. Following the hard reset, here are the numbers: altitude -68337, barometer 1013.2, temperature 561.

I realize that I may be the only person who has had this problem with every one of the devices. I wonder if there is something in the pool I use (salt water pool at Lifetime fitness) that degrades the sensors. I take impeccable care of the watch and rinse the sensor port under running fresh water after every workout. I'd rather not have these features on my watch than have these bizarrely wrong values and am not sure what to do at this point. I will call Garmin Monday and they will probably replace the device (hopefully). I love the functionality of the 5x and there is nothing out there that compares but I hate going through this repeatedly and am seriously considering switching platforms, though nothing out there appeals to the same degree.

I welcome suggestions.
  • Nothing you can do but rest assured, you're not the only one.
    I had to RMA 3 910XT in a row because of the altimeter... some just come off the production line in a poorly assembled phase. It doesn't have to do with salt water, it's a watch designed for swimming at sea... it's just a component that gets damaged more easily than others because even if we can't see it, it's basically out in the open.

    Contact tech support, be patient, get new watch. Happens.
  • Maybe the temperature reading went mad and that broke the whole altimeter calculation.
  • Nothing you can do but rest assured, you're not the only one.
    I had to RMA 3 910XT in a row because of the altimeter... some just come off the production line in a poorly assembled phase. It doesn't have to do with salt water, it's a watch designed for swimming at sea... it's just a component that gets damaged more easily than others because even if we can't see it, it's basically out in the open.

    Contact tech support, be patient, get new watch. Happens.


    Yes, probably true. However, I seem to be an outlier--each of these devices lasts me 4-6 months (or less) before developing the identical problem. Makes me think there is something I do that is particularly stressful to the sensor. Given how careful I am with the device, I can't help but wonder about chemicals or something else in the pool I use. I agree it is probably not the salt, per se.
  • Disappointing to hear. I asked DCRainmaker about this and he reckoned that some people seem to have this problem with multiple devices and some don't, but it really isn't clear exactly what the problem is. I had two 910XTs die with it, and two 920XTs so I'm evidently "one of them". On the plus side, Garmin were good about replacing the 910XTs and the first 920XT - but I had quite a battle over the second 920XT. I hoped that the Fenix line might be "sturdier"!

    I also looked at switching but Suunto and Polar have no plans to support ANT+ unfortunately.

    If anyone has any idea what causes this I'd love to know - obviously the barometer has to be more exposed so I can understand it's a bit more fragile, but you'd hope that Garmin would expect it to encounter sweat, saltwater, suncream, chlorine, energy drink etc. I've been absolutely religious at washing the barometer port on this latest watch after any exercise; previous ones have lasted 9-12 months so I'll have to see.

    In my own experience the breaks have occurred in March/April time which is usually just when I'm cranking up the swimming a bit, but haven't started to swim open water yet - so the watches have seen a bit of chlorine (though only 1-2x per week).


  • When I talked with Garmin yesterday, they acknowledged that there are a few of us and that there is a "case" open. Most of all, I would love to know what they find when I send these units back, and what, if anything, they could possibly tell us to avoid having this keep happening.
  • I hate to bring this up, but these aberrant elevation issues have been ongoing with the fenix 3HR (and to a seemingly lesser extent, the fenix 3) for nearly a year now. It seems to get much worse in cold weather. Garmin "has a case open" on this too with absolutely zero progress or updates since this issue was widely reported last September or so. There is/was widespread hope that this issue had been resolved for the fenix 5 series, but it would seem not...


  • As someone who has had a long history with these issues (as outlined in my original post) and has had two fenix 3HR units, I can say unequivocally that what I am describing is very different than the aberrations that have been widely described by 3HR owners. I experienced some of those also on the 3HR. However, those are more transient and behave differently. What I am describing is a total and permanent failure of A-B-T sensing. My current readings are unchanged at frozen values of altitude 1258 feet, barometric pressure 8030.3, and temperature of 561 degrees. In addition to the transient aberration problem, I also developed this same total sensor failure on one of the 3HR units I had. With all the postings related to the 3HR altimeter issues, I can't tell whether the total sensor failure that I am describing was also more common among 3HR users as well, but most of the postings are about the transient aberrations. The total sensor failure that I have unfortunately experienced on multiple devices now, including this 5x has nothing to do with cold ambient temperatures or any other aspect of weather. I am suspicious that it might be something in the pool that I have used for the past 5+ years, since I can't think of anything else that I do that would be that different than most other users. It is a "salt water" pool and as I pointed out above I rinse the port after every swim and every workout. I can't think of anything to do differently other than maybe to rinse the port even longer.... As also pointed out above, I do wish that Garmin would tell me what they find when they (hopefully) analyze the devices I return to them with this problem.
  • Update: I have received my replacement unit from Garmin, and it is working great. Garmin has always been very good about replacing these when I've had this problem. I would love to try and prevent a recurrence but am at wit's end as to what I can do differently. I've already been compulsive about rinsing out the port. All I can think to do is to rinse it out even longer. Then maybe I should be sure to shake or gently blow any moisture out of the port. I swim in a salt-water pool three times weekly and I assume that's the culprit. I would welcome additional recommendations.
  • What happens then if your unit was exchanged and you have bought some maps for say 200 eur? Because I understood that map is registered for device, so it stop working once device is exchanged. Does Garmin replace it?
    Any experience with this?