• Code: C3910
• Description: Backup memory data problem (scanner PWB) Data in the specified area of the backup memory does not match the specified values.
• Causes: Problem with the backup memory data. Defective scanner PWB.
• Remedy: Problem with the backup memory data. Run maintenance item U022 to initialize the backup memory data. Defective scanner PWB. If the C3910 is displayed after initializing the backup memory, replace the scanner PWB and check for correct operation.

• 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 YC8 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 YC8 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: C4200
• Description: BD steady-state problem ASIC detects a BD error A for 2 s after the polygon motor rotation has been stabilized.
• 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 YC8 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: C5300
• Description: Broken cleaning lamp wire While the cleaning lamp is on, the broken cleaning lamp wire detection signal is detected for 2 s continuously.
• Causes: Defective cleaning lamp. Defective engine PWB.
• Remedy: Defective cleaning lamp. Replace the cleaning lamp. Defective engine PWB. Replace the engine PWB and check for correct operation.

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

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

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