NTC3950 Thermistor Configuration

If you have purchased our NTC 3950 hex M3 stud thermistor to upgrade your China made 3D printer and wondering if you need to change anything in your printer configuration - there is nothing needs to be changed, it is drop-in replacement. It should work correctly as soon as you connect it. 

If you are going to re-configure and re-upload firmware, here is how to configure NTC 3950 100K thermistor for your firmware


Reconfigure your firmware for the NTC 3950 100K Thermistor: In configuration.h, for hotend use the following code:

  • #define TEMP_SENSOR_0 11

if you use NTC 3950 100K for heated bed, put this line instead:

  • #define TEMP_SENSOR_BED 11

For safety it is strongly recommended to do the following:

  • For hotend, set the minimum temperature to detect bad wiring (HEATER_0_MINTEMP 5 in configuration.h)

In newer versions of Marlin there are extra features for Thermal Runaway Protection should your thermistor come loose. Upload the new firmware to your electronics.


Use thermistor definition number 14, for extruder, put this line in the configuration:

  • #define EXT0_TEMPSENSOR_TYPE 14

For heated bed, use this code instead:


For safety it is strongly recommended to do the following:

  • Set the Minimum defect temperature to ensure that the thermistor shorting out is caught by the firmware.

New in Online Configuration Tool (v092) are the two options to also improve safety:

  • Decouple hold variance and Decouple min temp. rise to detect the thermistor coming loose. These must be set appropriately for your system to ensure that they work properly.

Upload the new firmware to your electronics.