Prusa 13206 on a MK4 3D printer: hotend MAXTEMP error

Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.

1. 1

   Let it cool fully

   No special tools

   Who:

   you.

   How:

   do not touch the toolhead: the printer cools itself down. Wait until the screen shows room temperature and switch it off before accessing anything, as Prusa asks.

   Result that matters:

   nozzle cold and machine off.

   If the temperature does not come down:

   unplug the printer and keep away from the toolhead.

   If it comes down normally:

   move on to the LoveBoard cables.

   Evidence to keep:

   photo of the screen with the error.

   Evidence: Prusa Knowledge Base: Hotend Maxtemp error #31206 (CORE One) #35206 (CORE One L) #26206 (MK4S) #13206 (MK4) #27206 (MK3.9S) #21206 (MK3.9) #28206 (MK3.5S) #23206 (MK3.5)

2. 2

   LoveBoard cables in view

   No special tools

   Who:

   you, if you follow Prusa's guide for your model.

   How:

   with the printer cold and off, access the LoveBoard (on the MK4 the cover slides upward) and check whether the heater and thermistor cables are properly connected and undamaged along their length.

   Result that matters:

   seated connectors and uncut cables.

   If you see a loose connector:

   reseat it with the printer off.

   If you see a damaged cable:

   do not repair it yourself; ask for the part.

   Evidence to keep:

   photos of the LoveBoard and cables.

   Evidence: Prusa Knowledge Base: Hotend Maxtemp error #31206 (CORE One) #35206 (CORE One L) #26206 (MK4S) #13206 (MK4) #27206 (MK3.9S) #21206 (MK3.9) #28206 (MK3.5S) #23206 (MK3.5)

3. 3

   Note the temperature and the moment

   No special tools

   Who:

   you.

   How:

   write down the nozzle temperature you had set and when the error appeared.

   Result that matters:

   whether the set temperature was far from 305 °C.

   If it was far:

   a jump like that points to the thermistor or its cables.

   If you were near the limit:

   tell support.

   Evidence to keep:

   note with set temperature and time.

   Evidence: Prusa Knowledge Base: Hotend Maxtemp error #31206 (CORE One) #35206 (CORE One L) #26206 (MK4S) #13206 (MK4) #27206 (MK3.9S) #21206 (MK3.9) #28206 (MK3.5S) #23206 (MK3.5)

A code is meaningful only inside the right product and version context.

Prusa explains this error appears when the nozzle temperature goes above 305 °C at any point. It is a safety feature to prevent damage: the print stops and the printer cools down. The screen asks you to check the print head thermistor wiring for damage, and Prusa says the error is usually caused by the hotend thermistor. It also asks you to check the cables at the LoveBoard, the extruder fuse and the LoveBoard main cable. It is 26206 on the MK4S and 31206 on the CORE One.

• Criticaleditorial warning

  Do not disable or bypass the thermal protection or change the firmware to clear the alert: it is what cuts the heat when the temperature does not add up. Do not open the printer's power supply or mains board: anything at mains voltage is for the service team.

  Evidence: Prusa Knowledge Base: Hotend Maxtemp error #31206 (CORE One) #35206 (CORE One L) #26206 (MK4S) #13206 (MK4) #27206 (MK3.9S) #21206 (MK3.9) #28206 (MK3.5S) #23206 (MK3.5)

• Highsource verified

  Prusa asks for the printer to be cooled down and switched off before you access any part or electronic board. The nozzle and the bed burn while they are hot.

  Evidence: Prusa Knowledge Base: Hotend Maxtemp error #31206 (CORE One) #35206 (CORE One L) #26206 (MK4S) #13206 (MK4) #27206 (MK3.9S) #21206 (MK3.9) #28206 (MK3.5S) #23206 (MK3.5)

1. 1

   Prusa Knowledge Base: Hotend Maxtemp error #31206 (CORE One) #35206 (CORE One L) #26206 (MK4S) #13206 (MK4) #27206 (MK3.9S) #21206 (MK3.9) #28206 (MK3.5S) #23206 (MK3.5)

   Prusa Research · 2026 · official_doc