393B4401

OKI B4401 Error 393: Drum Communication Failure

The OKI B4401 error 393 signals a critical communication breakdown between the printer and the image drum. Users often ask: Why does my OKI B4401 show error 393?, which is usually resolved by addressing dirty electrical contacts that prevent the machine from verifying the presence of the drum.

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Common causes

  • 1Dirty electrical contact pins.
  • 2Misalignment preventing full connection.
  • 3Damaged consumable chip.
  • 4Corrosion on internal printer contacts.

Solutions

Quick Diagnosis

The 393 code prevents the printer from starting, immediately identifying an issue with the imaging unit. If the printer hasn't been moved or serviced, dirt buildup on the connection pins is the primary suspect.

Step-by-Step Solution

  1. Turn off the printer.
  2. Carefully remove the drum and toner assembly.
  3. Clean the gold electrical pins on both the consumable and the printer frame with a dry cloth.
  4. Reinsert the unit securely.

Prevention and Maintenance

Always insert the drum cartridge gently to preserve the spring-loaded contacts. Keep the printer environment relatively clean to avoid excessive dust settling on delicate electronic components.

When to Call a Technician

If cleaning doesn't resolve the 393 error, the internal wiring or the printer's main engine control board might have a damaged connection trace.

Technical Specs

  • Technology: Monochrome Laser.
  • Speed: 40 ppm.
  • Connectivity: Ethernet/USB.
  • Capacity: 250 sheets standard.
  • Consumable: OKI B4400 drum series.
  • Usage: Corporate environments.
  • Drivers / firmware official

Steps to follow

  1. 1

    Remove drum

    Take out the toner and drum assembly from the printer.

  2. 2

    Clean contacts

    Use isopropyl alcohol to wipe the metallic connection pins.

  3. 3

    Reinsert carefully

    Install the unit back, ensuring it snaps into the correct position.

Frequently asked questions

Error 393 occurs when the printer fails to establish an electrical connection with the drum chip, often due to grime or misalignment.

Yes, cleaning the connection pins is usually all that is needed to resolve the communication error.

Yes, genuine OKI drums have reliable chips, whereas cheap compatibles often trigger this error.

Always hold the drum by its frame to avoid touching the sensitive contacts with fingers.