Kyocera KM-2050 Problem error C6400 - Kyocera Mita KM-5035 Printer

Fuser unit Error code, you can try to reset, but if the code still there, you need to change the fuser unit.
This is the way to reset your fuser code;
On the panel press 1087 1087
this will take you to the service mode,(look into the screen)
now on the panel again press 163 and hit the start key.
Look in the screen, you will see execute, select execute by the arrow and hit the start key, the machine will turn off then on. or it will ask you to turn the main power off than on. this might fix your problem, if not! change the fuser.

I’m happy to help further over the phone at https://www.6ya.com/expert/mustafa_06f84c65ab5cc745

Do this;
Press 10871087
dial 163
Excecute
your machine will power off then back on
while its powering on keep pressing ''system menu'' in sequence 1,2,3,4,5 times 6times 7times untill system menu appears then press copy or end and you should be good to go