840.02MS812dn

Lexmark MS812dn error 840.02: Diagnostic Guide

The Lexmark MS812dn error 840.02 is a warning regarding an abnormality in the network communication subsystem. It prevents the printer from being correctly identified in local networks, hindering print job flow. If you are wondering why is my Lexmark MS812dn showing error 840.02, follow our guide to restore your connectivity.

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Common causes

  • 1IP configuration error leading to packet flooding.
  • 2Firmware incompatibility with the local network router.
  • 3Physical damage to the network interface from power surges.
  • 4Corrupt network parameters stored in the printer's non-volatile memory.

Solutions

Quick Diagnosis

If the machine displays 840.02, look at the rear Ethernet port LED. If the link activity light is off despite a plugged-in cable, the logic board detects an internal communication hardware failure.

Step-by-Step Solution

  1. Remove the Ethernet cord for a few minutes while the machine is off.
  2. Power on the printer without the cable and observe if the error clears from the panel.
  3. If it does, ensure your network cable is not damaged and test it in another device.
  4. Enter the system network settings and execute a full network factory reset.

Prevention and Maintenance

Always secure network cables against pulls. Updating the firmware for the MS812dn is critical, as recent versions address common network-handshake failures in busy office environments.

When to Call a Technician

If the 840.02 persists after resetting the network configurations and verifying external hardware, the internal network controller chip has likely failed.

Technical Data

  • Technology: Monochrome Laser
  • Speed: Up to 70 ppm
  • Connectivity: Gigabit Ethernet / USB 2.0
  • Capacity: Max 4400 pages
  • Compatible Consumables: Lexmark 522, 524 Cartridges
  • Recommended Usage: Production print environments
  • Official Drivers / firmware

Steps to follow

  1. 1

    Network reset

    Disconnect the Ethernet cable and reboot the device.

  2. 2

    Test switch port

    Try connecting to a different wall or switch port.

  3. 3

    Update firmware

    Check the manufacturer support page for the latest system firmware.

  4. 4

    Reset TCP/IP

    Restore network settings to factory defaults through the panel menu.

Frequently asked questions

This code identifies a failure in the integrated network communication card, often resulting from IP address conflicts or firmware errors.

Yes, you can connect the printer using a USB cable to continue working while troubleshooting the Ethernet connection.

It uses Lexmark 522/524 series toner cartridges, built for heavy-duty professional environments.

Avoid moist environments and keep Ethernet ports free from dust accumulation to maintain stable signaling.