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Lexmark CX920

Lexmark CX920

900.00 firmware error with 121.45 machine check message

Issue description

The printer displays a with a 900.00 firmware error with a 121.45 machine check message as shown below.


If the error reoccurs, start the printer in the Diagnostics Mode with door C open and perform the following steps:

  1. Open the front cover.

  2. Turn OFF the printer using the power button on the left side (rocker switch).

  3. Press and hold the 3 and 6 buttons while turning ON the printer using the power button on the left side (rocket switch). Click here to see image of the step.

  4. Close the front door.

  5. Release the buttons when the splash screen appears. See image here.

  6. Screen will indicate DIAGNOSTICS MODE in the upper left hand corner if the sequence was performed correctly. If not, repeat, until you see the Lexmark screen.

  7. Enter the Diagnostics menu, and then navigate to:

    Printer setup > Reset Engine Service Error, then touch Start. Click here to see image.

  8. Slide the scroll bar to the top to Exit Diagnostic Menu.

  9. The printer will reboot.

  10. When the printer reboots, the Service Error will be cleared.

If you encounter this specific error, please make sure to contact Lexmark Support.


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