C440e-STUDIO 2309AHas video

How to Fix Toshiba e-STUDIO 2309A Error C440 (Fuser Reset)

The C440 error code on the Toshiba e-STUDIO 2309A indicates a fuser unit abnormality during the warming-up cycle. The temperature sensors detect that the fuser has failed to reach the required operation threshold within the allotted time, causing the mainboard to trigger a protective lock.

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Common causes

  • 1Defective fusing heater lamp or unstable power supply.
  • 2Open thermal cutout (thermostat) from previous overheating.
  • 3Accumulation of baked-on toner on the thermistor face.
  • 4Faulty fuser control circuit on the main board.

Solutions

When a C440 occurs, physical repairs must be completed before attempting to clear the fault code in the copier's software memory (08 mode). Fusing issues require cautious handling to prevent permanent component damage.

Hardware Inspection

  • Check Fuser Lamp & Thermostats: Measure resistance across the heater lamps and thermal cutoffs (thermostats) to ensure continuity.
  • Inspect Thermistors: Clean off any accumulated toner dust on the active face of the thermistor. Replace the thermistors if the contact surface is physically worn or scratched.

Clearing the Error via 08 Service Mode

  1. Turn off the copier.
  2. Press and hold down the 0 and 8 keys simultaneously while turning on the main power switch.
  3. Release the keys once the machine boots into the Test/Service Mode screen.
  4. Input code 400 (or 4000 for certain firmware variants) and hit the Start button.
  5. Select the current abnormal status value (typically displayed as 3 or higher) and change it to 0.
  6. Press Enter or OK to commit the change.
  7. Power cycle the machine normally.

Steps to follow

  1. 1

    Isolate the power supply

    Unplug the power cord and allow the fuser assembly to cool completely for at least 15 minutes before touch.

  2. 2

    Inspect and clean thermistors

    Remove the fuser unit, locate the primary and secondary thermistors, and clean them carefully with isopropyl alcohol.

  3. 3

    Access Service Code 08 Mode

    Boot the copier while holding down the 0 and 8 keys. Type code 400 once loaded.

  4. 4

    Reset state value to 0

    Change the non-zero status code back to 0 to unlock the heating cycle, save, and restart.

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Frequently asked questions

This indicates that the controller is still sensing a physical open circuit or zero temperature rise. Check the fuser lamps and thermostats for physical failures.

They are in the same family. C440 indicates a general heating delay, while C443 points specifically to an open circuit or abnormality in the main thermistor during active operation.