I just assembled my Ender 3 last night, this is my first printer and I’m new to this all. After about 10-15 minutes into printing it consistently gives me a thermal runaway error. Any help would be appreciated.

  • 2
    $\begingroup$ Is the part-cooling fan spinning ? $\endgroup$
    – Criggie
    Feb 19, 2022 at 22:16
  • 2
    $\begingroup$ Photo of the machine please? $\endgroup$
    – Trish
    Feb 19, 2022 at 22:42
  • $\begingroup$ The fan is spinning yea $\endgroup$
    – John Gaud
    Feb 19, 2022 at 23:00
  • $\begingroup$ Could you please select an answer or answer your own question if you solved the issue? $\endgroup$
    – Hacky
    Nov 22, 2022 at 14:04

1 Answer 1


Thermal runaway occurs when the hotend is on, but the sensor does not pickup any temperature increase. In many cases the thermistor is broken or the connection is bad. A friend of mine had the thermistor broken on his Ender 3 pro. It worked sometimes and sometimes not. Buy a new thermistor.(a few $ only) and replace it to be sure.


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