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Lexmark X950

Lexmark X950

An "Invalid Engine Code" error is appearing

What this error means

An Invalid Engine Code error indicates a problem with one of the internal operating programs of the printer. The printer will not be able to receive and process print jobs until the printer is reset. Follow the instructions below.

Reset the printer




Power off the printer.


Leave the printer powered off 30 seconds to one minute.


While the printer is off, please clear any unfinished print jobs that are currently in the software/network queue.


Power the printer back on. Allow time for the printer to get to the ready state. Do not send any print jobs to the printer at this time. Does the error occur when the power is turned back on?

  • NO - If the error does not occur on power-up, try printing again. If the error does not return during printing, this may have been an isolated incident. If the error does return, continue with step 5 below.
  • YES - Continue with step 5 below.


If the error message continue s, the printer may require an engine code update or possibly repair service to correct the issue. Please see the section below or contact Lexmark Technical Support for further assistance.

Download and update the engine code

In some cases, the engine code on the printer can become corrupted. If this occurs, resetting the printer will not resolve the issue. The engine code will need to be re-flashed to the printer. The engine code file can be downloaded to the printer even while the Invalid Engine Code message is displayed on the operator panel. NOTE: This is considered an "advanced" procedure, but it can be performed by a customer. However, if you feel uncomfortable about carrying out this procedure by yourself or encounter any problems with it, please contact Lexmark Technical Support for additional as sistance. See 'Contacting Lexmark' at the end of this document.




Put the printer in "flash engine" mode.

  1. Power the printer off.

  2. On the printer's operator panel, press and hold the left arrow button, the select button, and the right arrow button (highlighted in yellow in the image below).

  3. While keeping all three of these buttons held down, power the printer back on.

  4. Keep all three buttons held down until you see the messageInvalid Engine Code on the printer screen. At th at point, you can release the buttons.

  5. With the Invalid Engine Code message still displayed on the printer screen, you should now be able to safely flash the new engine code file to the printer.


To obtain the current engine code level, go to Lexmark's firmware download site. When prompted for the authorization key code, enter LSSTE211.

NOTE: The key code listed here is correct as of July 2007. If it does not work, please contact Lexmark Technical Support for the correct key code. See ' Contacting Lexmark' at the end of this document.


When you enter the authorization key code, the computer will begin downloading the file(s).

IMPORTANT! Some files can be very large. Please allow plenty of time, possibly up to half an hour, for downloading files when using a slower Internet connection speed.


Save the file(s) to a directory or folder of your choice. IMPORTANT! Make a note of the location.


Once you have downloaded the file(s), unzip any .zip files to extract the necessary engine code files and instructions.


You will need to copy the engine code file to the printer. The method to use depends on how your computer is connected to the printer. Refer to the instructions in the downloaded files. If the downloaded files do not include any instructions, choose appropriate link below for instructions. If copying engine or base code via:


Once you have updated the printer's engine code, power the printer off for 30 seconds to one minute. Then power it back on and try printing again.

  • If the printer works correctly, continue using it but observe it closely over the next couple of days to see if the error returns
  • If updating the engine code does not clear the error or if the error occurs again at a later date, the printer will require service. See 'Contacting Lexmark' below for more information.

Contacting Lexmark

If the printer requires service or if you need additional assistance with this issue, please contact Lexmark Technical Support. If you call Lexmark Technical Support for assistance with your printer, be prepared to describe the problem you are experiencing and any troubleshooting steps you have already taken.This information can be found on a label located on the inside of the printer, under the front cover. Please call from near the printer in case the technician asks you to perform a task involving the printer.


  • 40X3459 - System board assembly (non-network), T640 (4061-000)
  • 40X3460 - System board assembly (network), T640n (4061-010)
  • 40X3461 - Sys tem board assembly (non-network), T642 (4061-200)
  • 40X3462 - System board assembly (network), T642n (4061-210)
  • 40X3463 - System board assembly (non-network), T644 (4061-400)
  • 40X3464 - System board assembly (network), T644n (4061-410)

IMPORTANT! These part numbers are correct as of November 2006. Please confirm that they are still current and valid before ordering. If the part numbers listed here do not work, please see your next level of support or contact Lexmark Technical Support for the current part number.

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