• Code: C4501
• Description: Laser malfunction. • SOS signal is not detected even after the lapse of a given period of time after starting the laser output. • SOS signal is not detected for a given period of time during printing or IDC sensor adjustment.
• Causes: • PH unit • Printer control board (PRCB)
• Remedy: 1 Check the connector between PH unit-relay CN63- PRCB CN24 for proper connection and correct as necessary. 2 Replace the PH unit 3 Replace PRCB

• Code: C4801
• Description: Main unit board failure. MFP detects simultaneous replacement of multiple boards.
• Causes: • SSD board (SSDB) • Printer control board (PRCB)
• Remedy: 1 Reinstall the old PRCB. 2 If the above actions do not solve the problem, contact KM. NOTE • Do not replace the printer control board and the SSD board at the same time. The backup data is lost and image failure may be caused.

• Code: C4802
• Description: Main unit backup data miscompare. The replacement of the printer control board is detected.
• Causes: Printer control board (PRCB)
• Remedy: 1 1. When the finisher or job separator has been installed, remove it once. 2. Call the Enhanced Security in Service mode to the screen. 3. Touch [Engine Data Backup]. 4. Touch [Engine Data Reflect Mode], and press the Start key. 5. Select [Yes], and press the Start key again. 6. Check that the result “OK” appears. 7. Turn OFF the main power switch and turn it ON again more than 10 seconds after. 2 Update the PRCB firmware. 3 If the above actions do not solve the problem, contact KM.

• Code: C5102
• Description: Transport motor’s failure to turn. The motor lock signal remains HIGH for a predetermined continuous period of time while the motor is turning.
• Causes: • Transport motor (M1) • Printer control board (PRCB)
• Remedy: 1 Check the connector between M1-PRCB CN31 for proper connection and correct as necessary. 2 Check M1 for proper drive coupling and correct as necessary. 3 M1 operation check PRCB CN31-2 (REM) PRCB CN31-5 (LOCK) bizhub C554e 18-J bizhub C454e 16-J 4 Replace M1 5 Replace PRCB

• Code: C5103
• Description: Transport motor’s turning at abnormal timing. The motor lock signal remains LOW for a predetermined continuous period of time while the motor remains stationary.
• Causes: • Transport motor (M1) • Printer control board (PRCB)
• Remedy: 1 Check the connector between M1-PRCB CN31 for proper connection and correct as necessary. 2 Check M1 for proper drive coupling and correct as necessary. 3 M1 operation check PRCB CN31-2 (REM) PRCB CN31-5 (LOCK) bizhub C554e 18-J bizhub C454e 16-J 4 Replace M1 5 Replace PRCB

• Code: C5304
• Description: Fusing power supply cooling fan's failure to turn. <bizhub 554e> The fan lock signal remains HIGH for a predetermined continuous period of time while the fan is turning.
• Causes: • Fusing power supply cooling fan (FM12) • Expansion control board (EXCB) • Printer control board (PRCB)
• Remedy: 1 Check the connector between FM12-EXCB CN6 for proper connection and correct as necessary. 2 Check the fan for possible overload and correct as necessary. 3 FM12 operation check EXCB CN6-1 (REM) EXCB CN6-3 (LOCK) 23-T 4 Replace FM12 5 EXCB ICP1 conduction check 6 Replace EXCB 7 Replace PRCB

• Code: C5306
• Description: IH coil cooling fan's failure to turn. <bizhub 554e> The fan lock signal remains HIGH for a predetermined continuous period of time while the fan is turning.
• Causes: • IH coil cooling fan (FM7) • Expansion control board (EXCB) • Printer control board (PRCB)
• Remedy: 1 Check the connector between FS7-relay CN77-EXCB CN5 for proper connection and correct as necessary. 2 Check the fan for possible overload and correct as necessary. 3 FM7 operation check EXCB CN5-1 (REM) EXCB CN5-3 (LOCK) 23-T 4 Replace FM7 5 EXCB ICP1 conduction check 6 Replace EXCB 7 Replace PRCB

• Code: C5351
• Description: Power supply cooling fan motor’s failure to turn. The fan lock signal remains HIGH for a predetermined continuous period of time while the fan is turning.
• Causes: • Power supply cooling fan (FM1) • Printer control board (PRCB)
• Remedy: 1 Check the connector between FM1-relay CN26-PRCB CN18 for proper connection and correct as necessary. 2 Check the fan for possible overload and correct as necessary. 3 FM1 operation check PRCB CN18-13 (REM) PRCB CN18-15 (LOCK) 7-C 4 Replace FM1 5 PRCB ICP2 conduction check 6 Replace PRCB