Hi,
on 17.7.2 nano / x64 / CPU: AMD Sempron 200U
temperature doesnt show under the dashboard it only prints 
Core 0 (dev.cpu.0.temperature)
  (http://imgur.com/m4m9bDWl.png)
 (http://i.imgur.com/m4m9bDW.png)
but 
sysctl -a | grep temperature
dev.cpu.0.temperature: -49.0C
shows that.
			
			
			
				Hi bobbis,
Is -49 is a valid reading?  :)
Even so, the scale shows 0 (ice cold) to 100 (boiling hot), so I don't think it's exceptionally surprising that your reading is "0 or below".
Not sure what to do here...
Cheers,
Franco