• Code: C6410
• Description: Fixing unit connector insertion problem
  • Absence of the fixing unit is detected.
• Causes: Fixing unit connector inserted incorrectly. Defective fixing unit connector.
• Remedy: Reinsert the fixing unit connector if necessary. Replace the fixing unit.

• Code: C6420
• Description: Fixing unit fuse cut problem
  • The fixing temperature remains at 0 °C/32 °F for 30 s continuously when the fixing heater is on.
• Causes: Poor contact in the fixing unit thermistor connector terminals. Broken fixing unit thermistor wire.
• Remedy: Check the connection of connector YC10 on the main PCB and the continuity across the connector terminals. Repair or replace if necessary. Measure the resistance. If it is ∞Ω, replace the fixing unit thermistor.

• Code: C7300
• Description: Toner sensor problem
  • While the toner container sensor is on, the toner sensor in the developing unit does not turn on after the toner sensor turns off and toner is replenished from the toner container. (This code is not displayed. The service call counter counts the frequency of occurrence only as for this code.)
• Causes: Defective toner sensor. Poor contact in the toner sensor connector terminals. Defective toner container sensor. Defective toner container.
• Remedy: Replace the toner sensor. Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable. Replace the toner container sensor. Replace the toner container.

• Code: C7400
• Description: Image formation unit connector insertion problem
  • Absence of the image formation unit is detected.
• Causes: Image formation unit connector inserted incorrectly. Defective image formation unit connector.
• Remedy: Reinsert the image formation unit connector if necessary. Replace the image formation unit.

• Code: C7410
• Description: Drum unit connector insertion problem • Absence of the drum unit is detected.
• Causes: Drum unit connector inserted incorrectly. Defective drum unit connector.
• Remedy: Reinsert the drum unit connector if necessary. Replace the drum unit.

• Code: C7450
• Description: Image formation unit fuse cut problem • The input voltage is above 4.5 V.
• Causes: Image formation unit connector inserted incorrectly. Defective image formation unit connector.
• Remedy: Reinsert the image formation unit connector if necessary. Replace the image formation unit.

• Code: C7800
• Description: Broken external temperature thermistor wire • The input voltage is above 4.5 V.
• Causes: Poor contact in the humidity sensor PCB connector terminals. Defective external temperature thermistor.
• Remedy: Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable. Replace the humidity sensor PCB.

• Code: C7810
• Description: Short-circuited external temperature thermistor • The input voltage is below 1.0 V.
• Causes: Poor contact in the humidity sensor PCB connector terminals. Defective external temperature thermistor.
• Remedy: Reinsert the connector. Also check for continuity within the connector cable. If none, remedy or replace the cable. Replace the humidity sensor PCB.