EPU board memory old parts detection error: The EPU board cannot detect the new process unit when the equipment is started in the EPU replacement mode ( + [START]).
Thermistor or heater abnormality at power-ON: Abnormality of service call the thermistor is detected when power is turned ON or the temperature of the fuser roller does not rise in a specified period of time after power is turned ON.
Thermistor abnormality after abnormality judgment: Abnormality of the thermistor is detected after a specified period of time has passed from power-ON (including ready state).
Heater abnormality after abnormality judgment: The temperature of the fuser roller has exceeded the range of control or does not even reach the range.
Thermistor abnormality during printing: Abnormality of the thermistor is detected during printing.
Fuser unit new/old detection fuse abnormality
RADF I/F error: Communication error has occurred between the RADF and the scanner.
Document feeder model detection error: An optional document feeder that is not compatible to this equipment is installed.
Communication error between Engine-CPU and IPC board
Communication error between IPC board and finisher
EEPROM communication abnormality (LGC board)
ADF communication abnormality: The system has to be stopped because the control abnormality occurred
High-voltage transformer abnormality: Leakage of the main charger is detected.
Polygonal motor abnormality: The polygonal motor is not rotating normally.
These are the error cods list. If you wish to get some details; check the site linked here. Pull up older posts.