• Code: E4
• Description: Fuser unit error
  HTEMP remains high for longer than 4/2 seconds since the heater lamp is on. The heater lamp continues to be turn on for longer than 60/30 seconds.
• Causes: • Blown-out thermistor. • Blown-out heater lamp. • Defective CPU U201 or comparator U205 on the engine board. • Improper connector insertion. • Defective power supply unit. • Defective harness between fuser unit and power supply unit.

• Code: E5
• Description: Eraser lamp error
  The ERADEAD signal (delivered from the eraser lamp blownout detection circuit on the engine board) goes low continuously more than 1 second, while eraser lamp is on.
• Causes: • Blown-out eraser lamp [board KP-762]. • Defective CPU U201 on the engine board. • Improper connector insertion to the eraser lamp [board KP-762].

• Code: E9
• Description: Toner motor error
  Toner motor is overloaded. TNMOC is detected by sampling every other 100 ms in 2 seconds since the main and toner motors are activated following the Replace toner Clean printer message after the Toner low TK-60 is detected.
• Causes: • Overcurrent in the toner motor circuitry due to an excessive torque, caused by hardened toner. • Defective gate array U204 on the engine board. • Improper connector insertion. • Defective harness between developer and high voltage unit. • Defective harness between high voltage unit and engine board.

• Code: ED
• Description: Flash ROM error
  CPU U201 of engine board could not write data failed to flash ROM U202. Write sequence to flash ROM is not successful. Verify error. (Written data does not match the original data.)
• Causes: • Defective CPU U201 or gate array U204 or flash ROM U202 on the engine board (KP- 864).

• Code: F0
• Description: LCD controller board error
  Communication is failed between the LCD controller board (KP-738) and the main board.
• Causes: • Defective system DIMM [board KP-710*1/ KP-689*2]. • Defective main board (KP-777/KP-858). • LCD controller board (KP-738).

• Code: F1
• Description: System DIMM [board] error
  Checksum failed with system DIMM [board KP-710/KP-689] on the main board.
• Causes: • Defective system DIMM [board KP-710/ KP-689]. • Improper system DIMM [board KP-710/ KP-689] insertion to system DIMM slot on the main board (KP-777/KP-858).

• Code: F2
• Description: Main or expanded memory error
  Checksum failed with main memory (RAM) on the main board or expanded memory (DIMM).
• Causes: • Defective system main memory (RAM) on the main board (KP-777/KP-858). • Defective main board (KP-777/KP-858). • Defective expanding memory (DIMM) on the main board (KP-777/KP-858).

• Code: F3
• Description: General failure
  Miscellaneous failure with the main board, other than F0, F1 and F2, above.
• Causes: • Defective main board (KP-777/KP-858).