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Lexmark MX521

Lexmark MX521

843.00 or 843.01 scanner error

Issue description

A 843.00 or 843.01 scanner error appears on the printer’s control panel screen.

  • A POR resets the scanner system so the scan bars must re-home.
  • A Duplex Auto Document Feeder (DADF) designs includes two scan bars and their respective home sensors.
  • A failure of either scan bar to re-home will trigger a mechanical scanner failure declaration and one of these errors.


  1. Power off the printer.

  2. Leave the printer powered off for ten seconds.

  3. Power on the printer again.

  4. Open the flatbed scanner cover and watch the scanner bar (head) in the flatbed scanner. Confirm that it follows the correct startup sequence detailed below.

    • The scanner bar should move left and then right, and do so multiple times before stopping under the gray strip located on the left, between the Automatic Document Feeder (ADF) window and the flatbed window.
    • After that, the scanner bar should light up.
  5. Watch the operator panel to determine whether it is prompting 'Ready'. If it does, close the scanner cover and try using the scanner unit again.

    • If the scanner works, continue to use the printer as normal.
    • If the error message returns when you power the printer back on, contact Lexmark Technical Support for additional troubleshooting suggestions or possible service action for the scanner.
    • Note:  While waiting for a service action to be arranged, you can choose to disable the scanner unit and use the machine to print jobs from the computer. See the subsequent procedure on how to do this.

How to disable the scanner

This procedure is used to disable the Multifunction printer (MFP) scanner when it is malfunctioning.

  1. Access the printer’s Configuration Menu by pressing 2 and 6 buttons simultaneously on Power On Reset (POR).

  2. Select Disable Scanner from the Configuration menu.

  3. Scroll through the settings and select Disable.

  4. Select Submit.

  5. Restart the printer for the new settings to take effect.


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