• Code: C3851
• Description: Low Fuser Temperature Failure (Main)
  - The Fusing Roller Thermistor and Fusing Roller Sub Thermistor are detected to be at a temperature below 105 °C during standby.
  - The Fusing Roller Thermistor and Fusing Roller Sub Thermistor are detected to be at a temperature below 105 °C during printing.
• Remedy: 1 Check that the H1 comes on when the Right-Side Door is opened, then closed, and correct or replace as necessary. 2 Check that the H2 comes on when the Right-Side Door is opened, then closed, and correct or replace as necessary. 3 Check the installation of the TH1 and the TH2, and correct or clean as necessary. 4 Check the operation of the TH1. Remove CN80 (4P), and then check that the resistance across CN80-2 and -3 on the Thermistor is infinity. 5 Check the operation of the TH2. Remove CN81 (4P), and then check that the resistance across CN81-2 and -3 on the Thermistor is infinity. 6 Check the continuity of the H1. Correct or replace as necessary. 7 Check the continuity of the H2. Correct or replace as necessary. 8 Change PU1. 9 Change PWB-A.

• Code: C3852
• Description: Low Fuser Temperature Failure (Sub)
  - The Fusing Roller Thermistor and Fusing Roller Sub Thermistor are detected to be at a temperature below 105 °C during standby.
  - The Fusing Roller Thermistor and Fusing Roller Sub Thermistor are detected to be at a temperature below 105 °C during printing.
• Remedy: 1 Check that the H1 comes on when the Right-Side Door is opened, then closed, and correct or replace as necessary. 2 Check that the H2 comes on when the Right-Side Door is opened, then closed, and correct or replace as necessary. 3 Check the installation of the TH1 and the TH2, and correct or clean as necessary. 4 Check the operation of the TH1. Remove CN80 (4P), and then check that the resistance across CN80-2 and -3 on the Thermistor is infinity. 5 Check the operation of the TH2. Remove CN81 (4P), and then check that the resistance across CN81-2 and -3 on the Thermistor is infinity. 6 Check the continuity of the H1. Correct or replace as necessary. 7 Check the continuity of the H2. Correct or replace as necessary. 8 Change PU1. 9 Change PWB-A.

• Code: C4001
• Description: Main body Communication Failure
  Communications with the Mechanical Control Board and the MFBS Board/MFBS2 Board fail.
• Remedy: 1 Check the MFBS/MFBS2 connector for proper connection, and correct as necessary. 2 Check the PWB-A connector for proper connection, and correct as necessary. 3 Check the flat cable between MFBS/MFBS2 and PWB-A for proper connection, and correct as necessary. 4 Turn OFF the Main Power Switch, wait for 10 sec. or more, and turn ON the Main Power Switch. 5 Change MFBS/MFBS2. 6 Change PWB-A.

• Code: C4002
• Description: HSYNC Detection Failure
  - No SOS falling edges are detected within the set period of time after laser emission began while the Polygon Motor is turning.
  - No SOS falling edges are detected while VIA remains ON.
• Remedy: 1 Turn OFF the Main Power Switch, wait for 10 sec. or more, and turn ON the Main Power Switch. 2 Check the PH and the PWB-A connectors for proper connection, and correct as necessary. 3 Change PH. 4 Change PWB-A.

• Code: C4101
• Description: Polygon Motor Failure
  - The Polygon Motor Lock signal could not be detected within the set period of time after the Polygon Motor is energized. (Faulty start detection)
  - No First Lock signals are detected during the 1- second period that starts 1 second after a First Lock signal. (Faulty lock signal detection)
  - The Polygon Motor Lock signal could not be detected after the set period of time has elapsed while the Polygon Motor is turning. (Out-of-timing lock detection)
  - The Polygon Motor Lock signal is set to ON for longer than the set period of time while the Polygon Motor remains stopped. (Abnormal lock detection)
• Remedy: 1 Check the PH connector for proper connection, and correct as necessary. 2 Change PH. 3 Change PWB-A.

• Code: C4721
• Description: Main Body G/A Communication Failure
  - Communications with the gate array for expansion I/O (the IC mounted on the Mechanical Control Board) fail.
• Remedy: 1 Turn OFF the Main Power Switch, wait for 10 sec. or more, and turn ON the Main Power Switch. 2 Check each control board and the PWB-A for proper connection, and correct as necessary. 3 Change PWB-A.

• Code: C5102
• Description: Main Motor Failure
  - The Transport Motor Lock signal remains set to H for a set period of time while the Transport Motor is turning.
• Remedy: 1 Check the M1 connector for proper connection, and correct as necessary. 2 Check the M1 for proper drive coupling, and correct as necessary. 3 Check the PWB-A connector for proper connection and correct as necessary. 4 M1 operation check PWB-A PJ28A-4 (REM) M-4 5 Change PWB-A. 6 Change PU1.

• Code: C5351
• Description: Power Supply Cooling Fan Motor Failure
  - The Power Supply Cooling Fan Motor Lock signal remains set to H for a set period of time while the Power Supply Cooling Fan Motor is turning.
  - The Power Supply Cooling Fan Motor Lock signal remains set to L for a set period of time while the Power Supply Cooling Fan Motor remains stopped.
• Remedy: 1 Check the M4 connectors for proper connection, and correct as necessary. 2 Check the fan for possible overload, and correct as necessary. 3 M4 operation check PWB-A PJ33A-1 (REM) D-5 4 Change PU1.