• Code: C6020
• Description: Fuser thermistor high-temperature detection error
  • The fuser temperature exceeds 235C/455 F for 10 s.
• Causes: Installation defectiveness on fuser thermistor M and S.
  Defective fuser thermistor M and S.
  Defective engine PWB.
• Remedy: Installation defectiveness on fuser thermistor M and S. Check the mounting state of the fuser thermistor M and S. If any problem is found, repair it.
  Defective fuser thermistor M and S. Replace the fuser thermistor M and S.
  Defective engine PWB. Replace the engine PWB.

• Code: C6030
• Description: Fuser thermistor break error
  • The fuser temperature remains at lower then 0C/32F for 30 s continuously when the fuser heater is on.
• Causes: Defective engine PWB.
  Defective AC power source PWB.
  Installation defectiveness on fuser thermistor M and S.
• Remedy: Defective engine PWB. Replace the engine PWB.
  Defective AC power source PWB. Replace the AC power source PWB.
  Installation defectiveness on fuser thermistor M and S. Check the mounting state of the fuser thermistor M and S. If any problem is found, repair it.

• Code: C6050
• Description: Fuser thermistor abnormal temperature detection • During copying, the temperature at the heat roller lower than 120C/248F is detected continuously for 5 s.
• Causes: Installation defectiveness on fuser thermistor M and S.
  Operation on fuser thermostat 1 or 2.
  Installation defectiveness on fuser heater L, M or S.
  Broken fuser heater L, M and S wire.
  Defective engine PWB.
  Defective AC power source PWB.
• Remedy: Installation defectiveness on fuser thermistor M and S. Check the mounting state of the fuser thermistor M and S. If any problem is found, repair it.
  Operation on fuser thermostat 1 or 2. Check for continuity. If none, replace the fuser thermostat 1 or 2.
  Installation defectiveness on fuser heater L, M or S. Check the mounting state of the fuser thermistor L, M and S. If any problem is found, repair it.
  Broken fuser heater L, M and S wire. Check for continuity. If none, replace the fuser heater L, M and S.
  Defective engine PWB. Replace the engine PWB.
  Defective AC power source PWB. Replace the AC power source PWB.

• Code: C6400
• Description: Zero-cross signal error
  • The engine PWB does not detect the zero-crossing signal (Z CROSS SIG) for 5 s.
• Causes: Poor contact in the connector terminals.
  Defective DC power source PWB.
  Defective engine PWB
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC11 on the engine PWB and YC6 on the DC power source PWB, and the continuity across the connector terminals. Repair or replace if necessary.
  Defective DC power source PWB. Check if the zero-crossing signal is output from YC6-3 on the DC power source PWB. If not, replace the DC power source PCB.
  Defective engine PWB. Replace the engine PWB if C6400 is detected while YC6-3 on the DC power source PWB outputs the zero-crossing signal.

• Code: C7200
• Description: Broken internal thermistor wire
  • The thermistor output value is 4.5 V or more.
• Causes: Poor contact in the connector terminals.
  Defective developing humidity sensor.
  Defective engine PWB.
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC23 on the engine PWB and the continuity across the connector terminals. Repair or replace if necessary.
  Defective developing humidity sensor. Replace the developing humidity sensor.
  Defective engine PWB. Replace the engine PWB.

• Code: C7210
• Description: Short-circuited internal thermistor
  • The thermistor input value is 0.5 V or less.
• Causes: Poor contact in the connector terminals.
  Defective developing humidity sensor.
  Defective engine PWB.
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC23 on the engine PWB and the continuity across the connector terminals. Repair or replace if necessary.
  Defective developing humidity sensor. Replace the developing humidity sensor.
  Defective engine PWB. Replace the engine PWB.

• Code: C7300
• Description: Toner hopper problem
  • During toner replenishment after toner empty has been detected, toner empty could not be cleared in 3 times of 360 s.
• Causes: Defective toner level detection sensor.
  Poor contact in the toner level detection sensor connector terminals.
• Remedy: Defective toner level detection sensor. Replace the toner level detection sensor.
  Poor contact in the toner level detection sensor connector terminals. Check the connection of connectors YC2 and YC5 on the deck PWB and YC3 on the engine PWB. Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable.

• Code: C7800
• Description: Broken external thermistor wire
  • The thermistor output value is 4.5 V or more.
• Causes: Poor contact in the connector terminals.
  Defective humidity sensor.
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC13 on the engine PWB and the continuity across the connector terminals. Repair or replace if necessary.
  Defective humidity sensor. Replace the humidity sensor.