391OKI ES9520

Error 391 OKI ES9520: Transfer Belt Failure Solutions

The 391 error code on the OKI ES9520 indicates a detection failure in the Transfer Belt unit. This error typically occurs when the sensor fails to track the belt's rotation or due to physical blockage. The first recommended action is to power off the device and inspect the transfer area for paper debris or toner buildup.

1 views

Common causes

  • 1Excessive toner accumulation on the belt sensor preventing rotation pulse detection.
  • 2Physical obstruction from paper scraps stuck under the transfer unit.
  • 3Premature wear of belt bearings due to high-cycle industrial usage.
  • 4Electrical connection failure between the main board and the belt sensor.

Solutions

Diagnóstico rápido

The 391 error stops all printing processes and shows a blinking code on the front panel. Confirm this is the issue by ensuring the machine is not performing an extended calibration, as error 391 is a critical component failure regarding the belt transport system.

Solución paso a paso

  1. Power off the printer completely and unplug the power cord for 5 minutes to clear the error cache.
  2. Open the front cover and carefully remove the drum units to inspect the transfer belt.
  3. Clean the registration sensor using a soft, dry cloth, removing any toner dust obstructing the sensor path.
  4. Reinstall the drum units and ensure the belt is free of obstructions before powering on the device.

Prevención y mantenimiento

Clean the feed rollers weekly to prevent paper scraps from damaging the belt surface. Maintain room humidity between 40-60%, as dry air increases static electricity and sensor errors. Always use original consumables to prevent premature component wear.

Cuándo llamar a un técnico

If the 391 error persists after cleaning and rebooting, the belt motor may have failed or the sensor may be physically damaged. In these cases, professional technical service is required for internal parts replacement.

Ficha técnica del equipo

  • Technology: High-speed Digital LED Printing.
  • Speed/Performance: Up to 50 ppm (color and mono).
  • Connectivity: Ethernet 10/100/1000 Base-TX, USB 2.0.
  • Feeding Capacity: Standard tray 530 sheets; expandable up to 2950 sheets.
  • Compatible Consumables: OKI ES9520 Toner Series (CMYK), Drum Units ES9520 series.
  • Recommended Use: High-volume industrial and graphic arts environments.
  • Official drivers / firmware

Steps to follow

  1. 1

    Safety Power Down

    Switch off the unit and unplug from the power source to prevent damage to electronics.

  2. 2

    Belt Visual Inspection

    Remove the toner and drum cartridge to expose the belt; look for tears or paper scraps.

  3. 3

    Sensor Cleaning

    Use a lint-free microfiber cloth to gently wipe the registration sensor for accurate readings.

Frequently asked questions

Yes, it is a critical error. The printer cannot function until the system accurately detects the movement of the transfer belt.

Highly recommended. Low-quality compatible toners often leak fine particles that contaminate internal sensors quickly.

Use only low-pressure compressed air or a dry cloth. Never use alcohol or chemicals as they damage the transfer layer.

Professional cleaning is recommended every 20,000 prints or if you notice constant debris warnings on the panel.

Error 391 OKI ES9520: Transfer Belt Failure Solutions | Vimazdev