Exactly same issue as with 1040 in this topic https://forums.garmin.com/sports-fitness/cycling/f/edge-1040-series/397551/the-backlight-disrupts-the-temperature-reading
It also occurs on my 540 Solar, exactly the same - depending on backlight intensity, the temperature error can be as from 1 to 5 deg.C, When auto-backlight is On, you can't actually know how much the error is in current reading, this is quite annoying.
Since we run both 1040 and 540 (my wife's) we noticed the temperature readings are different on these 2 units while we ride together - obviously because we use different backlight settings (one unit is on auto-backlight, another one has auto-backlight off).
Garmin-Clayton you were asking about use-case for temperature, so I can explain here since you closed the original topic for investigation.
First, for trainings the temperature balance of one's body is essentiall, neither you should overheat or chill too much. During long rides knowing exact outside temperature is key, so that you can judge whether you should put up some additional layers of clothing, or remove. Especially if temp changes more than 5-7 degrees during a ride. Especially around freezing point - then you'd also watch out for black ice. My several rides this year were in mountains - starting from +28 deg.C on the coast, and going to +10 deg.C on top, so I knew I absolutely should not stop there for long but either go hard to generate a lot of heat, or turn back and descent immediately, despite my spare jacket in the bag. At +10 C I need to act differently compared to (if it was) +15 which I could have standed for long time no any issues. So you see 5 C error quite matters.
Pulling out your smartphone to check temperature online is not an option on the ride.
I've got another IQ datafield for temperature - Windfield, it shows temp at nearest weather station, but it can differ a lot due in coastal / forestal locations, I mean really a lot. So it's not that realiable. Another issue with weatherstation temperature - it shows just air temperature, but no sun-heat effect. While Garmin body does heat up in the sun and this is much more relevant to what your body feels under sunheat.
I guess this explains why Edge built-in temperature sensor reading is essential for those people who do training sessions, or long rides.
Please could you look at it and fix it, it seems to be a common issue for Edge devices.
For the record, both my 540 and 1040 are running latest software,25.24. I couldn't say if the problem were there with earlier software, because I didn't recognins that temperature reading irregularities were connected to baclkight so I didn't test it then.
Thank you!
