E04Fujitsu DL3750+Has video

Fujitsu DL3750+ Error E04 | APG Motor Diagnosis & Fix

The E04 error code on the Fujitsu DL3750+ indicates that the Automatic Paper Gap (APG) system cannot calibrate correctly. This typically points to a blocked carriage height sensor or mechanical resistance in the head spacing assembly.

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Common causes

  • 1Paper fibers or dried ink blocking the optical APG sensors.
  • 2Mechanical bind in the gears regulating head gap distances.
  • 3Defective APG stepper motor or faulty mainboard interface connection.

Solutions

Step 1: Clean Paper Dust and Debris

Continuous paper sheds fine dust that can blind optical gap sensors over time:
  1. Turn off the printer and pull out the power cord.
  2. Open the top cover and take out the ribbon cartridge.
  3. Blow compressed air carefully around the print head carriage assembly, focusing on the gear tracks and guide shaft.

Step 2: Check and Reset the APG Drive Gears

If the APG stepper motor detects physical strain or a locked gear, the controller boards triggers E04:
  1. Manually slide the print head carrier across the path to verify smooth movement.
  2. Locate the mechanical gap adjuster and gently alternate its setting between min and max to dislodge any stuck paper shreds.
  3. Plug the unit back in and run the power-up sequence to see if the self-test clears the alarm.

Steps to follow

  1. 1

    Power Off the Unit

    Switch off the printer and disconnect it from the electrical socket for safe service handling.

  2. 2

    Clear Optical Sensors

    Utilize dry compressed air on the carriage assembly to blow away debris interfering with the height detection sensors.

  3. 3

    Verify Free Gear Movement

    Manually shift the ribbon/gap assembly gears to ensure they turn freely and have no chipped teeth.

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Frequently asked questions

APG stands for Automatic Paper Gap. It automatically measures form thickness and adjusts the print head proximity to prevent paper tearing and optimize impact pressure.

In heavy-duty business environments, it is recommended to blow out dust from the printer internals once every 3 to 6 months to prevent E04 and E03 alerts.

Fujitsu DL3750+ Error E04 | APG Motor Diagnosis & Fix | Vimazdev