Hi there,
I am having issues with my 3d printers temperature detection. It's an Arduino and RAMPS running marlin with an e3d v6.
The temperature readings seem stable but can suddenly jump ~20-30?. I initially thought this was a connection problem of the thermistor so I checked the cables and didn't find any problems. This behaviour also happens whilst the effector is stationary, so the cables are stationary and so there shouldn't be any changes in connection quality causing different temperatures.
I also noticed that when I reset the printer, the temperature reading often swaps back to its previous value. Earlier today, I plugged in an SD card into the printer and the temperature immediately dropped ~30?. Then when removing the card, the temperature jumped straight back up. This seems very strange to me.

Any help would be much appreciated!
Thanks,
Tom.