• Code: 7231
• Description: Short-circuited LSU thermistor
  The sensor input sampling is less than 69.
• Causes: Defective connector cable or poor contact in the connector.
  Defective LSU thermistor.
  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. Laser scanner unit and LSU relay PWB (YC3) LSU relay PWB (YC2) and engine PWB (YC11)
  Defective LSU thermistor. Replace the laser scanner unit.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7241
• Description: Broken developer thermistor wire
  The sensor input sampling is greater than 230.
• Causes: Defective connector cable or poor contact in the connector.
  Defective developer thermistor.
  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. Developer unit and front PWB (YC7) Front PWB (YC2) and engine PWB (YC8)
  Defective developer thermistor. Replace developer unit.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7251
• Description: Short-circuited developer thermistor
  The sensor input sampling is less than 69.
• Causes: Defective connector cable or poor contact in the connector.
  Defective developer thermistor.
  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. Developer unit and front PWB (YC7) Front PWB (YC2) and engine PWB (YC8)
  Defective developer thermistor. Replace developer unit.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7301
• Description: Toner hopper motor error
  When the toner hopper motor is driven, toner hopper sensor does not turn on within 200 ms. This error is detected 15 times successively.
• Causes: Defective connector cable or poor contact in the connector.
  Defective drive transmission system of motor.
  Defective toner hopper sensor.
  Defective toner hopper motor.
  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. Toner hopper motor and front PWB (YC5) Front PWB (YC3) and engine PWB (YC7)
  Defective drive transmission system of motor. Check if the gears rotate smoothly. If not, grease the bushes and gears. Check for broken gears and replace if any.
  Defective toner hopper sensor. Replace the toner hopper sensor.
  Defective toner hopper motor. Replace the toner hopper motor.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: 7401
• Description: Developer unit type mismatch error
  Absence of the developer unit 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 and front PWB (YC7) Front PWB (YC2) and engine PWB (YC8)
  Different type of the developer unit is installed. Install the correct developer unit.

• Code: 7411
• Description: Drum unit type mismatch error
  Absence of the drum unit is detected.
• Causes: Defective connector cable or poor contact in the connector.
  Different type of the drum 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. Drum unit and front PWB (YC6) Front PWB (YC2) and engine PWB (YC8)
  Different type of the drum unit is installed. Install the correct drum unit.

• Code: 7460
• Description: Developer shutter error
  Power is turned on while the developer shutter is locked.
• Causes: The developer shutter has been locked.
  Defective connector cable or poor contact in the connector.
  
• Remedy: The developer shutter has been locked. Release the developer shutter.
  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 shutter sensor and front PWB (YC4) Front PWB (YC3) and engine PWB (YC7)

• Code: 7601
• Description: ID sensor error
  An abnormal value is detected in the input data to ID sensor.
• Causes: Defective connector cable or poor contact in the connector.
  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. ID sensor and relay PWB (YC10) Relay PWB (YC1) and feed PWB 1 (YC14) Feed PWB 1 (YC2) and engine PWB (YC5)
  Defective engine PWB. Replace the engine PWB and check for correct operation.