Mmmm, I see what you are talking about, interesting it could be you have a defective temp reader,

Let's move the temp3 to P3 and check if you are getting correct numbers on temp2 to confirm it is indeed a defective reader.

In the mean time also, to prevent the unit from overheating. you can shift the two adjustable fans to FAN4 and FAN5, which will run them at full speed ( could be a bit loud but it is a good temporary solution. )

and if temp2 also reports 0 after switching, then we can confirm that this is caused by a defective temp reader and we'll just mail you a new one.