Kyocera 820i C3900 Error

[Tonerkiller]

The EEPROM solved the problem for me.

Which eeprom

[qtech]

Greetings all, I know this is an old thread, but I recently had a 3550ci throwing the C3900 code. No standard resets or FW upgrades would cure it, but replacing the ISC board did the trick for me. Just putting it out there in hopes it helps someone else.......
Chris