As much as I love my 945 it's burning my wrist. I brought my watch at the end of July 2020. I get on well with it but on a couple of occasions now the sensor is burning my wrist.

Looks more like some kind of alergic rash to me. Make sure you clean the watch with anti-bacterial soap frequently, and desinfect it time to time. I doubt it could be due to the heat, because you would then see a very rapid discharging of the battery.

After you have given what trux has suggested a thorough test and you're still experiencing issues, see below from Garmin support. Also I've moved this thread to the 945 forum.

Any user who experiences any sort of skin irritation will need to reach out to us directly at support.garmin.com. We will need to gather information from you that we would not ask for in a public forum. These complaints are taken seriously and we will work to find the most suitable solution as quickly as possible. 

same for me. I see huge purple bruise in the morning, which subsides during the day and reappears tomorrow. I suppose it is PulseOx sensor to blame — it works only at night and burns my skin.

4737408 said:

I suppose it is PulseOx sensor to blame — it works only at night and burns my skin.

See the above replies. I do not believe it could be caused by the PulseOx sensor, since the energy needed for such a burn would drain the battery pretty fast. An alergic or a bacterial rash are much more likely. Contact the Support if keeping the watch clean, and changing the wrists regularly does not help.

I had exactly the same rash on my wrist. I wear my watch 24/7 the solution for me was change your watch to your other wrist during the night you get all the metrics except the rash :). 

I agree with the other posters - it is unlikely to be the sensor light, there is just not enough power.

However, if you look carefully at the sensor, you will notice it is raised and is the part of the watch that it in closest contact with your skin. It is also furthest away from the edge of the watch. In short, if you are wearing it 24/7, the skin has no opportunity to breathe.

I agree with the other suggestions:

• rinse the watch thoroughly in fresh water, especially after a sweaty run.
• If you want to wear the watch overnight for sleep metrics, switch it to the other wrist. This will give the opportunity for the skin under the wrist to breathe.

I've Had this problem a lot. (It's Bacteria according to my Doctor)

The Only thing that worked for me is cleaning the Watch With +- 70 % Rubbing Alcohol Ever Activity and Every Morning.

I Also Clean my Wrists at the same time with the same fluid.

Soap and Water did NOT work for me.

JoeD said:

The Only thing that worked for me is cleaning the Watch With +- 70 % Rubbing Alcohol Ever Activity and Every Morning.

The rubbing alcohol is a big no-no especially on the resin that covers the sensor.  Have you tried an anti-bacterial soap?  Much easier on both your watch and skin and will accomplish the same thing.