• Code: 7101
• Description: Toner sensor K error
  The sensor outputs are for 5 seconds, 23 or less, or 248 or more.
• Causes: Defective Developer unit. Defective PWB.
• Remedy: Defective Developer unit. Replace the developer unit K.
  Defective PWB. Replace the engine PWB check for correct operation.

• Code: 7102
• Description: Toner sensor C error
  The sensor outputs are for 5 seconds, 23 or less, or 248 or more.
• Causes: Defective Developer unit. Defective PWB.
• Remedy: Defective Developer unit. Replace the developer unit C.
  Defective PWB. Replace the engine PWB check for correct operation.

• Code: 7103
• Description: Toner sensor M error
  The sensor outputs are for 5 seconds, 23 or less, or 248 or more.
• Causes: Defective Developer unit. Defective PWB.
• Remedy: Defective Developer unit. Replace the developer unit M
  Defective PWB. Replace the engine PWB check for correct operation.

• Code: 7104
• Description: Toner sensor Y error
  The sensor outputs are for 5 seconds, 23 or less, or 248 or more.
• Causes: Defective Developer unit. Defective PWB.
• Remedy: Defective Developer unit. Replace the developer unit Y.
  Defective PWB. Replace the engine PWB check for correct operation.

• Code: 7401
• Description: Developer unit K type mismatch error
  Absence of the developer unit K is detected.
• Causes: Defective connector cable or poor contact in the connector. Different type of the developer unit is installed.
• 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. Developer unit K and drum connect PWB (YC9) Drum connect PWB and engine PWB (YC4)
  Different type of the developer unit is installed. Install the correct developer unit.

• Code: 7402
• Description: Developer unit C type mismatch error
  Absence of the developer unit C is detected.
• Causes: Defective connector cable or poor contact in the connector. Different type of the developer unit is installed.
• 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. Developer unit C and drum connect PWB (YC7) Drum connect PWB and engine PWB (YC4)
  Different type of the developer unit is installed. Install the correct developer unit.

• Code: 7403
• Description: Developer unit M type mismatch error
  Absence of the developer unit M is detected.
• Causes: Defective connector cable or poor contact in the connector. Different type of the developer unit is installed.
• 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. Developer unit M and drum connect PWB (YC8) Drum connect PWB and engine PWB (YC4)
  Different type of the developer unit is installed. Install the correct developer unit.

• Code: 7404
• Description: Developer unit Y type mismatch error
  Absence of the developer unit Y is detected.
• Causes: Defective connector cable or poor contact in the connector. Different type of the developer unit is installed.
• 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. Developer unit Y and drum connect PWB (YC6) Drum connect PWB and engine PWB (YC4)
  Different type of the developer unit is installed. Install the correct developer unit.