integrated temperature sensor doesn't work

I know this doesn't help, but if the temperature sensor doesn't work, then the barometric altimeter will also give incorrect results...

could you tell me, how I can check result of Altimeter or Barometric ? Use on other gadgets?

I access it by scrolling through watch faces to get to 'ABC'    (altimeter & compass)

Here is how to setup your Widgets on your watch faces.  Go to add a widget and choose ABC

https://www8.garmin.com/manuals/webhelp/forerunner945/EN-US/GUID-61C825F5-5D80-413F-BA3F-CD8C51BB63F2.html

You can also add the datafield Elevation or something like that to a screen within your activity settings for run/bike/walk etc.  I often have an entire screen with a few elevation based fields (Elevation, total gain, lap gain, etc)

https://www8.garmin.com/manuals/webhelp/forerunner945/EN-US/GUID-638CD68D-11B0-4D9C-B8B7-E28D15EC4566.html

Try the diagnostic mode

Switch off the watch
Hold Down button
Whilst holding down button, power up the watch with a longish press of the light button
Keep Down button held whilst Garmin logo is displayed.
This will open up diagnostic mode

My wife has the 945 so, although I know the diagnostic mode works, I can't walk you through the pages to see where the temp sensor is validated.  As Bitti notes, if the temp sensor is screwed so is the altimeter readings.  Have you tried the various resets 9starting with the really long press of the power button?

Hello,

Ive got same problem but it happens only after pool swim. Then temperature reading is gone. I restart the watch and itś back. It doen happen with open water. It happens aldo outside the pool....

This is deliberately disabled.

forums.garmin.com/.../1307177