• Code: C4000
• Description: Polygon motor synchronization problem
  The polygon motor does not reach the stable speed within 20 s of the START signal turning on.
• Causes: Poor contact in the connector terminals.
  Defective polygon motor.
  Defective engine PWB.
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC3 on the engine PWB and laser scanner unit, and the continuity across the connector terminals. Repair or replace if necessary.
  Defective polygon motor. Replace the laser scanner unit.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: C4010
• Description: Polygon motor steady-state problem
  Stable OFF is detected for 20 s continuously after polygon motor stability.
• Causes: Poor contact in the connector terminals.
  Defective polygon motor.
  Defective engine PWB.
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC3 on the engine PWB and laser scanner unit, and the continuity across the connector terminals. Repair or replace if necessary.
  Defective polygon motor. Replace the laser scanner unit.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: C4100
• Description: BD initialization problem
  5 consecutive BD errors were detected during an 800 ms interval after the polygon motor stabilized.
• Causes: Poor contact in the connector terminals.
  Defective polygon motor.
  Defective engine PWB.
• Remedy: Poor contact in the connector terminals. Check the connection of connector YC3 on the engine PWB and laser scanner unit, and the continuity across the connector terminals. Repair or replace if necessary.
  Defective polygon motor. Replace the laser scanner unit.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: C6000
• Description: Fuser heater break
  Fuser thermistor 1 detected less than 70°C/158°F for 10 s during warm-up and ready in. During warm-up, the temperature at the fuser unit thermistor 1 does not rise by 1°C/1.8°F continuously for 5 s. Fuser thermistor 2 detected less than 40°C/104°F for 10 s during warm-up and ready in. During warm-up, the temperature at the fuser unit thermistor 2 does not rise by 1°C/1.8°F continuously for 5 s.
• Causes: Defective fuser heater 1 or 2.
  Installation defectiveness on fuser thermistor 1.
  Defective fuser thermostat.
  Defective PWB.
• Remedy: Defective fuser heater 1 or 2. Replace the fuser heater 1 or 2.
  Installation defectiveness on fuser thermistor 1. Check the mounting state of the fuser thermistor 1. If any problem is found, repair it.
  Defective fuser thermostat. Replace the fuser thermostat.
  Defective PWB. Replace the power source PWB or engine PWB and check for correct operation.

• Code: C6020
• Description: Abnormally high fuser thermistor temperature
  Fuser thermistor 1 or 2 is detected 250°C/482°F or more for 40 ms.
• Causes: Installation defectiveness on fuser thermistor 1 or 2.
  Defective fuser thermistor unit 1 or 2.
  Defective engine PWB.
• Remedy: Installation defectiveness on fuser thermistor 1 or 2. Check the mounting state of the fuser thermistor 1 or 2. If any problem is found, repair it.
  Defective fuser thermistor unit 1 or 2. Replace the fuser thermistor 1 or 2.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: C6030
• Description: Fuser thermistor break error
  The fuser thermistor break signal is detected continuously for 1 s.
• Causes: Installation defectiveness on fuser thermistor 1 or 2.
  Defective fuser thermistor 1 or 2.
  Defective engine PWB.
• Remedy: Installation defectiveness on fuser thermistor 1 or 2. Check the mounting state of the fuser thermistor 1 or 2. If any problem is found, repair it.
  Defective fuser thermistor 1 or 2. Replace the fuser thermistor 1 or 2.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: C6040
• Description: Fuser thermistor 1 detection error
  Fuser thermistor 1 detected an abnormal value for at least 1 s.
• Causes: Installation defectiveness on fuser thermistor 1.
  Defective fuser thermistor 1.
  Defective engine PWB.
• Remedy: Installation defectiveness on fuser thermistor 1. Check the mounting state of the fuser thermistor 1. If any problem is found, repair it.
  Defective fuser thermistor 1. Replace the fuser thermistor 1.
  Defective engine PWB. Replace the engine PWB and check for correct operation.

• Code: C6050
• Description: Abnormally low fuser thermistor temperature
  Fuser thermistor 1 is detected 80°C/ 176°F less than 1 s continuously during copying.
• Causes: Defective fuser heater 1 or 2.
  Installation defectiveness on fuser thermistor 1.
  Defective PWB.
• Remedy: Defective fuser heater 1 or 2. Replace the fuser heater 1 or 2.
  Installation defectiveness on fuser thermistor 1. Check the mounting state of the fuser thermistor 1. If any problem is found, repair it.
  Defective PWB. Replace the power source PWB or engine PWB and check for correct operation.