• Code: 7401
• Description: Developer unit type Mismatch error (Black) Improper adaptation of the main unit and developer unit is detected.
• Remedy: Developer unit 1. Check if the developer unit of different models is mounted, and replace it to the correct one. 2. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Developer unit - Unit relay PWB Unit relay PWB - Main/Engine PWB(YC7) 3. If the wiring is disconnected, short-circuited or has a ground fault, replace the wire.
  Unit relay PWB Replace the unit relay PWB.
  Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the main/engine PWB.

• Code: 7402
• Description: Developer unit type Mismatch error (Cyan) Improper adaptation of the main unit and developer unit is detected.
• Remedy: Developer unit 1. Check if the developer unit of different models is mounted, and replace it to the correct one. 2. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Developer unit - Unit relay PWB Unit relay PWB - Main/Engine PWB(YC7) 3. If the wiring is disconnected, short-circuited or has a ground fault, replace the wire.
  Unit relay PWB Replace the unit relay PWB.
  Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the main/engine PWB.

• Code: 7403
• Description: Developer unit type Mismatch error (Magenta) Improper adaptation of the main unit and developer unit is detected.
• Remedy: Developer unit 1. Check if the developer unit of different models is mounted, and replace it to the correct one. 2. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Developer unit - Unit relay PWB Unit relay PWB - Main/Engine PWB(YC7) 3. If the wiring is disconnected, short-circuited or has a ground fault, replace the wire.
  Unit relay PWB Replace the unit relay PWB.
  Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the main/engine PWB.

• Code: 7404
• Description: Developer unit type mismatch error (Yellow) Improper adaptation of the main unit and developer unit is detected.
• Remedy: Developer unit 1. Check if the developer unit of different models is mounted, and replace it to the correct one. 2. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Developer unit - Unit relay PWB Unit relay PWB - Main/Engine PWB(YC7) 3. If the wiring is disconnected, short-circuited or has a ground fault, replace the wire.
  Unit relay PWB Replace the unit relay PWB.
  Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the main/engine PWB.

• Code: 7411
• Description: Drum unit type Mismatch error (Black) Improper adaptation of the main unit and drum unit is detected.
• Remedy: Drum unit 1. Check if the drum unit of different models is attached, and replace it to the correct one. 2. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Drum unit - Unit relay PWB Unit relay PWB - Main/Engine PWB(YC7) 3. If the wiring is disconnected, short-circuited or has a ground fault, replace the wire.
  Unit relay PWB Replace the unit relay PWB.
  Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the main/engine PWB.

• Code: 7412
• Description: Drum unit type Mismatch error (Cyan) Improper adaptation of the main unit and drum unit is detected.
• Remedy: Drum unit 1. Check if the drum unit of different models is attached, and replace it to the correct one. 2. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Drum unit - Unit relay PWB Unit relay PWB - Main/Engine PWB(YC7) 3. If the wiring is disconnected, short-circuited or has a ground fault, replace the wire.
  Unit relay PWB Replace the unit relay PWB.
  Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the main/engine PWB.

• Code: 7413
• Description: Drum unit type Mismatch error (Magenta) Improper adaptation of the main unit and drum unit is detected.
• Remedy: Drum unit 1. Check if the drum unit of different models is attached, and replace it to the correct one. 2. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Drum unit - Unit relay PWB Unit relay PWB - Main/Engine PWB(YC7) 3. If the wiring is disconnected, short-circuited or has a ground fault, replace the wire.
  Unit relay PWB Replace the unit relay PWB.
  Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the main/engine PWB.
  

• Code: 7414
• Description: Drum unit type Mismatch error (Yellow) Improper adaptation of the main unit and drum unit is detected.
• Remedy: Drum unit 1. Check if the drum unit of different models is attached, and replace it to the correct one. 2. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Drum unit - Unit relay PWB Unit relay PWB - Main/Engine PWB(YC7) 3. If the wiring is disconnected, short-circuited or has a ground fault, replace the wire.
  Unit relay PWB Replace the unit relay PWB.
  Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the main/engine PWB.