• Code: C7104
• Description: T/C sensor Y error Object: Color models
• Causes: For the specified value of the initial toner stored in the EEPROM of the developer unit, the output value of the T/C sensor is out of the range between +100 (undetection toner) and -1000 (Coming off of the sensor connector). And that status was detected 3 times continuously.
• Remedy: 1 Reinstalling the developer unit The developer unit is not properly installed. Reinstall developer unit Y so that the connector firmly connects. Developer Unit Replacement 2 Checking the wire The wire is not properly connected or is faulty. Reinsert the following wire connectors, and replace the wires when they have no continuity.• Drum/developer relay PWB - Feed image PWB• Feed image PWB - Engine PWB Electrical Diagram of PWBs 3 Replacing the drive gear The drive gear for developer unit Y is damaged. (The spiral is not rotated.) Replace the drive gear for developer unit Y. 4 Developer unit replacement Developer unit Y (T/C sensor Y) is faulty. Replace the developer unit Y. Developer Unit Replacement 5 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Upgrade 6 Replacing the drum/developer relay PWB The drum/developer relay PWB is faulty. Replace the drum/developer relay PWB. Drum/ Developer Relay PWB Replacement 7 Replacing the feed image PWB The feed image PWB is faulty. Replace the feed image PWB. 8 Replacing the engine PWB The engine PWB is faulty. Replace the engine PWB. Engine PWB Replacement

• Code: C7200
• Description: Inner thermistor broken (developer)
• Causes: The input sampling value of T/C sensor BK (inner thermistor) is at the reference value or more.
• Remedy: 1 Reinstalling the developer unit The developer unit is not properly installed. Reinstall developer unit BK so that the connector firmly connects. Developer Unit Replacement 2 Checking the wire The wire is not properly connected or is faulty. Reinsert the following wire connectors, and replace the wires when they have no continuity.• Drum/developer relay PWB - Feed image PWB• Feed image PWB - Engine PWB Electrical Diagram of PWBs 3 Developer unit replacement Developer unit BK (T/C sensor BK) is faulty. Replace the developer unit BK. Developer Unit Replacement 4 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Upgrade 5 Replacing the drum/developer relay PWB The drum/developer relay PWB is faulty. Replace the drum/developer relay PWB. Drum/ Developer Relay PWB Replacement 6 Replacing the feed image PWB The feed image PWB is faulty. Replace the feed image PWB.

• Code: C7210
• Description: Inner thermistor short-circuited (developer)
• Causes: The input sampling value of T/C sensor BK (inner thermistor) is the reference value or less.
• Remedy: 1 Reinstalling the developer unit The developer unit is not properly installed. Reinstall developer unit BK so that the connector firmly connects. Developer Unit Replacement 2 Checking the wire The wire is not properly connected or is faulty. Reinsert the following wire connectors, and replace the wires when they have no continuity.• Drum/developer relay PWB - Feed image PWB• Feed image PWB - Engine PWB Electrical Diagram of PWBs 3 Developer unit replacement Developer unit BK (T/C sensor BK) is faulty. Replace the developer unit BK. Developer Unit Replacement 4 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Upgrade 5 Replacing the drum/developer relay PWB The drum/developer relay PWB is faulty. Replace the drum/developer relay PWB. Drum/ Developer Relay PWB Replacement 6 Replacing the feed image PWB The feed image PWB is faulty. Replace the feed image PWB

• Code: C7221
• Description: LSU thermistor broken
• Causes: The input sampling value of the LSU thermistor is at the reference value or more.
• Remedy: Checking the FFC The FFC is not properly connected, or it is faulty. Reconnect the following FFC. When the FFC terminals are peeled off or deformed or the FFC is broken, replace the FFC.• LSU - Engine PWB Electrical Diagram of PWBs 2 LSU replacement The LSU (LSU thermistor) is faulty. Replace the LSU. LSU Replacement 3 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Upgrade 4 Replacing the engine PWB The engine PWB is faulty. Replace the engine PWB. Engine PWB Replacement

• Code: C7231
• Description: LSU thermistor short-circuited
• Causes: The input sampling value of the LSU thermistor is at the reference value or less.
• Remedy: 1 Checking the FFC The FFC is not properly connected, or it is faulty. Reconnect the following FFC. When the FFC terminals are peeled off or deformed or the FFC is broken, replace the FFC.• LSU - Engine PWB Electrical Diagram of PWBs 2 LSU replacement The LSU (LSU thermistor) is faulty. Replace the LSU. LSU Replacement 3 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Upgrade 4 Replacing the engine PWB The engine PWB is faulty. Replace the engine PWB. Engine PWB Replacement

• Code: C7241
• Description: Belt thermistor broken
• Causes: The input sampling value of the belt thermistor is at the reference value or more.
• Remedy: 1 Reinstalling the primary transfer unit The primary transfer unit is not properly installed. Reinstall the primary transfer unit so that the connector firmly connects. Primary Transfer Unit Replacement 2 Checking the wire The wire is not properly connected or is faulty. Reinsert the following wire connectors, and replace the wires when they have no continuity.• Transfer PWB - Transfer connection PWB• Transfer connection PWB - Feed image PWB Electrical Diagram of PWBs 3 Primary transfer unit replacement The primary transfer unit is faulty. Replace the primary transfer unit. Primary Transfer Unit Replacement 4 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Upgrade 5 Replacing the transfer connection PWB The transfer connection PWB is faulty. Replace the transfer connection PWB. 6 Replacing the feed image PWB The feed image PWB is faulty. Replace the feed image PWB.

• Code: C7251
• Description: Belt thermistor short-circuited
• Causes: The input sampling value of the belt thermistor is at the reference value or less.
• Remedy: 1 Reinstalling the primary transfer unit The primary transfer unit is not properly installed. Reinstall the primary transfer unit so that the connector firmly connects. Primary Transfer Unit Replacement 2 Checking the wire The wire is not properly connected or is faulty. Reinsert the following wire connectors, and replace the wires when they have no continuity.• Transfer PWB - Transfer connection PWB• Transfer connection PWB - Feed image PWB Electrical Diagram of PWBs 3 Primary transfer unit replacement The primary transfer unit is faulty. Replace the primary transfer unit. Primary Transfer Unit Replacement 4 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Upgrade 5 Replacing the transfer connection PWB The transfer connection PWB is faulty. Replace the transfer connection PWB. 6 Replacing the feed image PWB The feed image PWB is faulty. Replace the feed image PWB.

• Code: C7301
• Description: Toner motor BK error
• Causes: The toner supply motor drive stopped and waited for 0.1s when the pulse plate of the toner supply screw could not detect the pulse for 2s during the toner supply motor operation. Even if these operations repeated 3 times continuously, the pulse could not be detected.
• Remedy: 1 Checking the toner supply drive unit The toner supply screw is not rotated properly due to the excessive load. (The pulse plate is not rotated.) Check if the toner is not clogged inside the toner supply drive unit by rotating the toner supply screw manually. Then, clean the unit if necessary. 2 Checking the wire The wire is not properly connected or is faulty. Reinsert the following wire connectors, and replace the wire if there is no continuity.• Toner motor BK - Feed image PWB Electrical Diagram of PWBs 3 Replacing the toner supply drive unit The toner supply drive unit (toner motor BK or toner level sensor BK) is faulty. Replace the toner supply drive unit. Toner Supply Drive Unit Replacement 4 Firmware upgrade The firmware is not the latest version. Upgrade the engine firmware to the latest version Firmware Upgrade 5 Replacing the feed image PWB The feed image PWB is faulty. Replace the feed image PWB.