• Code: 5900
• Description: Rechecking the error after the power switch was turned OFF and then ON again because an error was detected by the center thermistor of the fuser unit. (This message is displayed for approximately 15 minutes when the machine is restarted after error code 5800 has occurred.)
• Causes: 1 Connection failure of the fuser unit harnesses. 2 Connection failure of the eject sensor PCB harness. 3 Fuser unit failure. 4 Eject sensor PCB failure. 5 Low-voltage power supply PCB failure. 6 Main PCB failure.
• Remedy: 1 Connection failure of the fuser unit harnesses Check the connection of fuser unit harnesses, and reconnect them if necessary. 2 Connection failure of the eject sensor PCB harness Check the connection of the eject sensor PCB harness, and reconnect it if necessary. 3 Fuser unit failure Replace the fuser unit. 4 Eject sensor PCB failure Refer to "1.3.10 Check sensor operation (function code: 32)" in Chapter 5 to check the sensor operation. If the sensor operation is faulty, replace the eject sensor PCB ASSY. 5 Low-voltage power supply PCB failure Replace the low-voltage power supply PCB ASSY. 6 Main PCB failure Replace the main PCB ASSY.

• Code: 6300
• Description: The toner sensor detected no toner remaining or the number of rotations of the developer roller has reached the upper limit.
• Causes: 1 Toner sensor PCB failure. 2 Relay front PCB failure. 3 Main PCB failure.
• Remedy: 1 Toner sensor PCB failure Refer to "1.3.10 Check sensor operation (function code: 32)" in Chapter 5 to check the sensor operation. If the sensor operation is faulty, replace the toner sensor PCB ASSY. 2 Relay front PCB failure Replace the relay front PCB ASSY. 3 Main PCB failure Replace the main PCB ASSY.

• Code: 6700
• Description: The toner sensor detected that the toner remaining has fallen below the specified level or the developer roller counter has exceeded the specified value.
• Causes: 1 Toner sensor PCB failure. 2 Relay front PCB failure. 3 Main PCB failure.
• Remedy: 1 Toner sensor PCB failure Refer to "1.3.10 Check sensor operation (function code: 32)" in Chapter 5 to check the sensor operation. If the sensor operation is faulty, replace the toner sensor PCB ASSY. 2 Relay front PCB failure Replace the relay front PCB ASSY. 3 Main PCB failure Replace the main PCB ASSY.

• Code: 6A00
• Description: The center thermistor of the fuser unit has not reached the specified temperature within the specified time.
• Causes: 1 Connection failure of the center or side thermistor harness of the fuser unit. 2 Connection failure of the heater harness of the fuser unit. 3 Connection failure of the eject sensor PCB harness. 4 Connection failure of the lowvoltage power supply PCB harness. 5 Eject sensor PCB failure. 6 Fuser unit failure. 7 Low-voltage power supply PCB failure. 8 Main PCB failure.
• Remedy: 1 Connection failure of the center or side thermistor harness of the fuser unit Check the connection of the center or side thermistor harness of the fuser unit, and reconnect it if necessary. 2 Connection failure of the heater harness of the fuser unit Check the connection of the heater harness of the fuser unit, and reconnect it if necessary. 3 Connection failure of the eject sensor PCB harness Check the connection of the eject sensor PCB harness, and reconnect it if necessary. 4 Connection failure of the lowvoltage power supply PCB harness Check the connection of the low-voltage power supply PCB harness, and reconnect it if necessary. 5 Eject sensor PCB failure Refer to "1.3.10 Check sensor operation (function code: 32)" in Chapter 5 to check the sensor operation. If the sensor operation is faulty, replace the eject sensor PCB ASSY. 6 Fuser unit failure Replace the fuser unit. 7 Low-voltage power supply PCB failure Replace the low-voltage power supply PCB ASSY. 8 Main PCB failure Replace the main PCB ASSY.

• Code: 6B00
• Description: The center thermistor of the fuser unit has not reached the specified temperature within the specified time.
• Causes: 1 Connection failure of the center or side thermistor harness of the fuser unit. 2 Connection failure of the heater harness of the fuser unit. 3 Connection failure of the eject sensor PCB harness. 4 Connection failure of the lowvoltage power supply PCB harness. 5 Eject sensor PCB failure. 6 Fuser unit failure. 7 Low-voltage power supply PCB failure. 8 Main PCB failure.
• Remedy: 1 Connection failure of the center or side thermistor harness of the fuser unit Check the connection of the center or side thermistor harness of the fuser unit, and reconnect it if necessary. 2 Connection failure of the heater harness of the fuser unit Check the connection of the heater harness of the fuser unit, and reconnect it if necessary. 3 Connection failure of the eject sensor PCB harness Check the connection of the eject sensor PCB harness, and reconnect it if necessary. 4 Connection failure of the lowvoltage power supply PCB harness Check the connection of the low-voltage power supply PCB harness, and reconnect it if necessary. 5 Eject sensor PCB failure Refer to "1.3.10 Check sensor operation (function code: 32)" in Chapter 5 to check the sensor operation. If the sensor operation is faulty, replace the eject sensor PCB ASSY. 6 Fuser unit failure Replace the fuser unit. 7 Low-voltage power supply PCB failure Replace the low-voltage power supply PCB ASSY. 8 Main PCB failure Replace the main PCB ASSY.

• Code: 6C00
• Description: The center thermistor of the fuser unit detected a temperature higher than the specified value.
• Causes: 1 Connection failure of the center or side thermistor harness of the fuser unit. 2 Connection failure of the heater harness of the fuser unit. 3 Connection failure of the eject sensor PCB harness. 4 Connection failure of the lowvoltage power supply PCB harness. 5 Eject sensor PCB failure. 6 Fuser unit failure. 7 Low-voltage power supply PCB failure. 8 Main PCB failure.
• Remedy: 1 Connection failure of the center or side thermistor harness of the fuser unit Check the connection of the center or side thermistor harness of the fuser unit, and reconnect it if necessary. 2 Connection failure of the heater harness of the fuser unit Check the connection of the heater harness of the fuser unit, and reconnect it if necessary. 3 Connection failure of the eject sensor PCB harness Check the connection of the eject sensor PCB harness, and reconnect it if necessary. 4 Connection failure of the lowvoltage power supply PCB harness Check the connection of the low-voltage power supply PCB harness, and reconnect it if necessary. 5 Eject sensor PCB failure Refer to "1.3.10 Check sensor operation (function code: 32)" in Chapter 5 to check the sensor operation. If the sensor operation is faulty, replace the eject sensor PCB ASSY. 6 Fuser unit failure Replace the fuser unit. 7 Low-voltage power supply PCB failure Replace the low-voltage power supply PCB ASSY. 8 Main PCB failure Replace the main PCB ASSY.

• Code: 6D00
• Description: After the heat unit was heated normally, the center thermistor of the fuser unit detected a temperature lower than the specified value.
• Causes: 1 Connection failure of the center or side thermistor harness of the fuser unit. 2 Connection failure of the heater harness of the fuser unit. 3 Connection failure of the eject sensor PCB harness. 4 Connection failure of the lowvoltage power supply PCB harness. 5 Eject sensor PCB failure. 6 Fuser unit failure. 7 Low-voltage power supply PCB failure. 8 Main PCB failure.
• Remedy: 1 Connection failure of the center or side thermistor harness of the fuser unit Check the connection of the center or side thermistor harness of the fuser unit, and reconnect it if necessary. 2 Connection failure of the heater harness of the fuser unit Check the connection of the heater harness of the fuser unit, and reconnect it if necessary. 3 Connection failure of the eject sensor PCB harness Check the connection of the eject sensor PCB harness, and reconnect it if necessary. 4 Connection failure of the lowvoltage power supply PCB harness Check the connection of the low-voltage power supply PCB harness, and reconnect it if necessary. 5 Eject sensor PCB failure Refer to "1.3.10 Check sensor operation (function code: 32)" in Chapter 5 to check the sensor operation. If the sensor operation is faulty, replace the eject sensor PCB ASSY. 6 Fuser unit failure Replace the fuser unit. 7 Low-voltage power supply PCB failure Replace the low-voltage power supply PCB ASSY. 8 Main PCB failure Replace the main PCB ASSY.

• Code: 6E00
• Description: The center thermistor of the fuser unit detected that the heat unit was not heated.
• Causes: 1 Connection failure of the center or side thermistor harness of the fuser unit. 2 Connection failure of the heater harness of the fuser unit. 3 Connection failure of the eject sensor PCB harness. 4 Connection failure of the lowvoltage power supply PCB harness. 5 Eject sensor PCB failure. 6 Fuser unit failure. 7 Low-voltage power supply PCB failure. 8 Main PCB failure.
• Remedy: 1 Connection failure of the center or side thermistor harness of the fuser unit Check the connection of the center or side thermistor harness of the fuser unit, and reconnect it if necessary. 2 Connection failure of the heater harness of the fuser unit Check the connection of the heater harness of the fuser unit, and reconnect it if necessary. 3 Connection failure of the eject sensor PCB harness Check the connection of the eject sensor PCB harness, and reconnect it if necessary. 4 Connection failure of the lowvoltage power supply PCB harness Check the connection of the low-voltage power supply PCB harness, and reconnect it if necessary. 5 Eject sensor PCB failure Refer to "1.3.10 Check sensor operation (function code: 32)" in Chapter 5 to check the sensor operation. If the sensor operation is faulty, replace the eject sensor PCB ASSY. 6 Fuser unit failure Replace the fuser unit. 7 Low-voltage power supply PCB failure Replace the low-voltage power supply PCB ASSY. 8 Main PCB failure Replace the main PCB ASSY.