Replacing a Thermistor

A malfunctioning thermistor can cause the following issues:

Inaccurate hotend temperature (0°C or inf°C)

Connection failure

To replace a thermistor

1. Turn the printer off using the switch and disconnect the power cable.
2. Remove the printhead lid (article).
3. Disconnect the power and thermistor cables.
4. Use a Phillips screwdriver to loosen the bolt keeping the Hotend in place and pull it out.
5. Remove the silicon sock covering the heat block and loosen the thermistor screw using an Allen wrench.
6. Be cautious not to damage the cables when pulling out the old thermistor and inserting the new one while aligning its tip with the heat block.
7. Tighten the thermistor screw until you feel a slight resistance to avoid causing any unwanted damage to it and slip on the silicon sock again.
8. Fasten the Hotend screw again while pushing the Hotend upwards.
9. Connect the power and thermistor cables again.
10. Put the printhead lid back on.

Where to find new thermistors

The Portrait uses original e3D thermistors which can be purchased from e3D directly via this link.