• Code: C7104
• Description: Toner sensor Y problem
  Sensor output value of 60 or less or 944 or more continued for 3 s.
• Causes: Defective developing unit Y.
  Defective PWB
• Remedy: Defective developing unit Y. Replace the developing unit Y.
  Defective PWB. Replace the sub front PWB or engine PWB and check for correct operation.

• Code: C7200
• Description: Broken internal thermistor wire
  An abnormal value is detected in the input data to inner temperature sensor 1.
• Causes: Poor contact in the connector terminals
  Defective laser scanner unit.
  Defective engine PWB.
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC13 on the engine PWB and laser scanner unit, and the continuity across the connector terminals. Repair or replace if necessary.
  Defective laser scanner unit. Replace the laser scanner unit.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: C7210
• Description: Short-circuited internal thermistor
  An abnormal value is detected in the input data to inner temperature sensor 1.
• Causes: Poor contact in the connector terminals.
  Defective laser scanner unit.
  Defective engine PWB.
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC13 on the engine PWB and laser scanner unit, and the continuity across the connector terminals. Repair or replace if necessary.
  Defective laser scanner unit. Replace the laser scanner unit.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: C7240
• Description: Broken internal thermistor 2 wire
  An abnormal value is detected in the input data to inner temperature sensor 2.
• Causes: Poor contact in the connector terminals.
  Defective engine PWB
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC8 on the engine PWB and the continuity across the connector terminals. Repair or replace if necessary.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: C7250
• Description: Short-circuited internal thermistor 2
  An abnormal value is detected in the input data to inner temperature sensor 2.
• Causes: Poor contact in the connector terminals.
  Defective engine PWB.
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC8 on the engine PWB and the continuity across the connector terminals. Repair or replace if necessary.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: C7401
• Description: Developing unit K type mismatch problem
  Absence of the developing unit K is detected.
• Causes: Developing unit connector inserted incorrectly.
  Different type of the developing unit is installed.
• Remedy: Developing unit connector inserted incorrectly. Reinsert the developing unit connector if necessary.
  Different type of the developing unit is installed. Install the correct developing unit.

• Code: C7402
• Description: Developing unit C type mismatch problem
  Absence of the developing unit C is detected.
• Causes: Developing unit connector inserted incorrectly.
  Different type of the developing unit is installed.
• Remedy: Developing unit connector inserted incorrectly. Reinsert the developing unit connector if necessary.
  Different type of the developing unit is installed. Install the correct developing unit.

• Code: C7403
• Description: Developing unit M type mismatch problem
  Absence of the developing unit M is detected.
• Causes: Developing unit connector inserted incorrectly.
  Different type of the developing unit is installed.
• Remedy: Developing unit connector inserted incorrectly. Reinsert the developing unit connector if necessary.
  Different type of the developing unit is installed. Install the correct developing unit.