Hotend preheat error #26202 (MK4S) #13202 (MK4) #21202 (MK3.9)

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What happened?

The printer is showing the message "Hotend preheat error: Check the print head heater and thermistor wiring for potential damage"

Error name: Hotend preheat error

Error code: #26202 (MK4S) #13202 (MK4) #21202 (MK3.9)

This error is shown when the printer is unable to heat up the nozzle more than 2 ºC for 20 seconds. The printer starts a safety feature, which instantly kills the heating process and displays the message on the screen. The printer then waits for the user to inspect all parts and if needed fix the issue.

How to fix it?

Make sure that the ambient temperature where the printer is is stable, and above 10 ºC.

Extruder inspection

This error can be caused by any damage to the hotend heater or the hotend thermistor.

Access the LoveBoard and check the heater and thermistor cables. Make sure that they are connected correctly and that there is no damage along their length.

xBuddy board inspection

On the MK4/MK3.9 main board, check if the fuse that protects the extruder is not damaged.

Make sure that the Loveboard main cable is correctly connected to the xBuddy board.

Multimeter check

In case you have a multimeter available, use this guide to check the resistance on the hotend heater and the hotend thermistor.