• Code: 7402
• Description: Developing unit C noninstalling error
  No density detection signal is output from toner sensor C in developing unit C.
• Causes: Defective connector cable or poor contact in the connector. Defective toner sensor C. Defective engine PWB.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Developing unit C and Drum relay PWB (YC10) Drum relay PWB (YC1) and engine PWB (YC34)
  Defective toner sensor C. Replace the developing unit C.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7403
• Description: Developing unit M noninstalling error
  No density detection signal is output from toner sensor M in developing unit M.
• Causes: Defective connector cable or poor contact in the connector. Defective toner sensor M. Defective engine PWB.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Developing unit M and Drum relay PWB (YC7) Drum relay PWB (YC1) and engine PWB (YC34)
  Defective toner sensor M. Replace the developing unit M.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7404
• Description: Developing unit Y noninstalling error
  No density detection signal is output from toner sensor Y in developing unit Y.
• Causes: Defective connector cable or poor contact in the connector. Defective toner sensor Y. Defective engine PWB.
• Remedy: Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Developing unit Y and Drum relay PWB (YC13) Drum relay PWB (YC1) and engine PWB (YC34)
  Defective toner sensor Y. Replace the developing unit Y.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7411
• Description: Drum unit K non- installing error
  The EEPROM of drum PWB K does not communicate normally.
• Causes: Installation of incompatible drum unit K. Defective connector cable or poor contact in the connector. Defective drum PWB K. Defective engine PWB.
• Remedy: Installation of incompatible drum unit K. Install drum unit K compatible with the specifications to the machine.
  Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum unit K and Drum relay PWB (YC2) Drum relay PWB (YC1) and engine PWB (YC34)
  Defective drum PWB K. Replace the drum unit K.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7412
• Description: Drum unit C non- installing error
  The EEPROM of drum PWB C does not communicate normally.
• Causes: Installation of incompatible drum unit C. Defective connector cable or poor contact in the connector. Defective drum PWB C. Defective engine PWB.
• Remedy: Installation of incompatible drum unit C. Install drum unit C compatible with the specifications to the machine.
  Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum unit C and Drum relay PWB (YC4) Drum relay PWB (YC1) and engine PWB (YC34)
  Defective drum PWB C. Replace the drum unit C.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7413
• Description: Drum unit M non- installing error
  The EEPROM of drum PWB M does not communicate normally.
• Causes: Installation of incompatible drum unit M. Defective connector cable or poor contact in the connector. Defective drum PWB M. Defective engine PWB.
• Remedy: Installation of incompatible drum unit M. Install drum unit M compatible with the specifications to the machine.
  Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum unit M and Drum relay PWB (YC3) Drum relay PWB (YC1) and engine PWB (YC34)
  Defective drum PWB M. Replace the drum unit M.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7414
• Description: Drum unit Y non- installing error
  The EEPROM of drum PWB Y does not communicate normally.
• Causes: Installation of incompatible drum unit Y. Defective connector cable or poor contact in the connector. Defective drum PWB Y. Defective engine PWB.
• Remedy: Installation of incompatible drum unit Y. Install drum unit Y compatible with the specifications to the machine.
  Defective connector cable or poor contact in the connector. Reinsert the connector. Also check for continuity within the connector cable. If none, replace the cable. Drum unit Y and Drum relay PWB (YC5) Drum relay PWB (YC1) and engine PWB (YC34)
  Defective drum PWB Y. Replace the drum unit Y.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 9500 ... 9520
• Description: Contact the Service Administrative Division.
• Causes:
• Remedy: Contact the Service Administrative Division.