bbkkth

Yes gr5, you are right. I tried to pull the sensor cable and deform it a little bit, then I could see changes in the magnitude of temperature swings. But if it is a common problem, then what do you guys do to fix it and prevent it the next time?

Thanks Jonny and gr5 for your helpful replies. Do you think that other than hardware (that's very likely as you said), any firmware bug can cause this kind of problems? The reason that I suspect the firmware can cause this is that we haven't used the printer for a long time but I upgraded the marlin firmware 3 times since we got the printer.

Hello everybody, We are having the same problem of unstable nozzle temperature. We bought our UM2 one month ago and it was printing very well until yesterday. Now without printing I try to heat up the nozzle and see if the temperature reaches the target temp or not, when set to 210 degrees it has a fluctuation of +-10 degrees. Please let me know how is the nozzle temperature control procedure in UM2, is the fan behind the nozzle used to control the temperature or the temperature is only controlled by the heating element? Another question is that which fan are we setting in Cura, 2 side fans or the fan at the back of the nozzle? Hope to hear good news about your printers!