• Code: 7222
• Description: Broken inner thermistor (LSU Cyan & Yellow) The sensor input sampling is greater than the reference value. (After detection, controlled at 25°C/77.0 °F)
• Remedy: LSU (Cyan & Yellow) 1. Confirm that the wiring connector of LSU (Cyan & Yellow) is firmly connected, and if necessary, connect the connector all the way in. LSU (Cyan & Yellow) and Main/Engine PWB (YC2017) 2. If the wire is disconnected, short-circuited or has ground fault, or the connector pin is deformed, replace the wire. 3. Replace the LSU (Cyan & Yellow).
  Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the Main/Engine PWB.

• Code: 7401
• Description: Developer unit K type mismatch error (Black) Improper adaptation of the main unit and developer unit is detected.
• Remedy: Developer unit K Check if the developer unit of different models is mounted, and replace it to the correct one.

• Code: 7402
• Description: Developer unit C type mismatch error (Cyan) Improper adaptation of the main unit and developer unit is detected.
• Remedy: Developer unit C Check if the developer unit of different models is mounted, and replace it to the correct one.

• Code: 7403
• Description: Developer unit M type mismatch error (Magenta) Improper adaptation of the main unit and developer unit is detected.
• Remedy: Developer unit M Check if the developer unit of different models is mounted, and replace it to the correct one.

• Code: 7404
• Description: Developer unit Y type mismatch error (Yellow) Improper adaptation of the main unit and developer unit is detected.
• Remedy: Developer unit Y Check if the developer unit of different models is mounted, and replace it to the correct one.

• Code: 7411
• Description: Drum unit K type mismatch error (Black) Improper adaptation of the main unit and drum unit is detected.
• Remedy: Drum unit K Check if the drum unit of different models is attached, and replace it to the correct one.

• Code: 7412
• Description: Drum unit C type mismatch error (Cyan) Improper adaptation of the main unit and drum unit is detected.
• Remedy: Drum unit C Check if the drum unit of different models is attached, and replace it to the correct one.

• Code: 7413
• Description: Drum unit M type mismatch error (Magenta) Improper adaptation of the main unit and drum unit is detected.
• Remedy: Drum unit M Check if the drum unit of different models is attached, and replace it to the correct one.