Firstly, I just bought a G2S mini pro from Geeetech and it is my first 3D printer (therefore I'm 100% newbie in this area).

The first extruder seems to be ok, the temperature varies from 23°C to 201°C and if you touch it you can see that it is hot. However, for the second extruder, the temperature is shown with more than 400°C:

Second extruder at 400°C

The cables are connected correctly and the firmware is updated.

Do I have to return the printer? Or is there another solution?


If you have access to an IR thermometer, it would be interesting to verify what the actual temperature is. I doubt the hot end actually reaches that temperature, but:

  • if it actually does, then it could actually be dangerous, as most extruders are designed for temperatures well below 300°C. The problem would likely be in the firmware in this case.
  • if it stays cold, then probably is a problem with the temperature probe or its cables/connectors being broken. Most printers use thermistors as temperature probes, and thermistors let less and less current pass through the higher the temperature is, so: no current would be interpreted as the hot end being "extremely hot" and the firmware would not heat the hot end further.
  • if it is hot but at another temperature than the one displayed, then it could either be a problem with the probe over-reading or a firmware bug (e.g.: the temperature is shown in Fahrenheit, or the firmware mis-process the signal from the probe).

Either way: thermistors and cables are cheap to replace, while problems with the firmware may be fixed only if you have access to the code.

If you just bought the printer in a physical store, I would simply swap it with another unit, rather than fiddling with it, though.

  • $\begingroup$ The tempeature is cold, but the cable is connected... $\endgroup$ – Hola Soy Edu Feliz Navidad Feb 3 '18 at 20:07
  • $\begingroup$ @HolaSoyEduFelizNavidad - the cable could be broken inside, the connector could be defective, the thermistor could be broken... A tester can help diagnosing where the circuit is interrupted... but replacing the unit (if it is an option for you) seems the cheapsst surefire option... $\endgroup$ – mac Feb 3 '18 at 22:49

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