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Firmware Download and Update Precautions and Instructions for the Lexmark CS43x and CX43x Series MFPs (October 2021)

Document ID:RE288

Usergroup :External


Read first!

  • It is strongly recommended that a firmware downgrade is NOT performed.
  • Downgrading firmware from newer major firmware ECs to older major firmware ECs will result in the loss of Apps, Security Features, and Settings.

For more information about... See...
How to identify installed apps and backup your configuration settings... KB Article# HO4031
The dangers of downgrading firmware... KB Article# SO8017

  • Also, upgrading firmware requires that you update any non-native apps to their latest respective versions except for Fax Forward, Google Cloud Print and Email to Self. These apps are integral to EC1(FW3), but the .02x.yyy. versions of these apps need to be uninstalled to avoid conflicting versions..


Firmware availability (October 2021)

Models Latest firmware level (FW7.5)

Standard base models:



Release notes

Standard base models:



Release notes

DLE*- equipped models

For example:

  • Forms and Barcode
  • Prescribe
  • IPDS

Contact Lexmark Technical Support


Read Firmware update instructions if unfamiliar or uncertain of the firmware update procedure.

NOTE: Periodic printer firmware updates address end-user performance issues, provide new functionality, and provide performance improvements. Firmware updates may modify printer settings and cause counterfeit and/or unauthorized products to stop working; i.e., supplies, parts, materials (such as toners and inks), software, or interfaces. Authorized use of genuine products will not be affected. 


Still need help?

If you need additional assistance, please go to the Lexmark support site, type your printer model and locate Get in Touch with Lexmark! for contact information. NOTE: When calling for support, you will need the following: 

  • Name and version of the solution
  • Affected printer model/s
  • Printer serial number

Please be near the product/s described in this article to expedite the support process and reduce callbacks.



Firmware update instructions

Step 1:
Identify current code levels and follow the decisions below. See "How to check printer firmware levels".   

Important upgrade decisions:  



Firmware is outdated and I do not have a special build of firmware or a printer equipped with a DLE... Review the release notes to identify a product improvement or necessary fix, and continue to Step 2 below. 

I have code installed that is not recognized in this article, or I have had a special build of firmware provided by members of Lexmark's product engineering team...

  1. Review the release notes to identify a needed fix or function. 

  2. Proceed to Step 2 only if you have confirmed the presence of the fix or function provided by your special build of firmware. 

  3. Contact Lexmark Technical Support if you need additional confirmation that this upgrade is safe.

I have DLE- specific firmware code...

Installed DLE as seen under Device Information

Examples of DLE options include Prescribe, IPDS, and Forms and Barcode (FMBC).

DLEs are base-code dependent, so

  1. Review the release notes to identify a needed fix or function.

  2. Contact Lexmark Technical Support to request a DLE-specific version of this code level.

  3. You will be asked what type of DLE card is installed in the device.

  4. Click here if you installed a DLE and received an error.



Step 2: Download and extract the .zip file. See Firmware download above, and then continue to Step 3 if not familiar with firmware flash methods.

The .zip file contains the following files:


Step 3: Update the printer using one of the following fls. update methods:  

Make sure the printer is READY to receive firmware, and do not interrupt the printer's power or data connection during the update process.  

Firmware flash methods (.fls file extensions)


Recommended use

The device Web page or embedded Web server (EWS

Open your Internet browser and enter the device's IP address. Select Settings > Update Firmware.

Click here for an example.

This is the preferred firmware update method if:

  • The device is connected to your network, and

  • HTTP (port 80) is enabled allowing you to access its EWS, and

  • Access controls are not limiting remote management.

USB utility

Click here for an example.

This is an alternative flash method for USB-attached printers in a Microsoft environment.

USB thumb drive

Click here for an example.

This alternative flash method is used only if:

  • You have a standalone device, and

  • No access to a computer, and

  • Access controls are not limiting flash drive access.


Click here for detailed steps.

This alternative flash method is used only if:

  • The device has HTTP (EWS) disabled, and

  • There is no access to a Microsoft Windows computer, and

  • FTP (port 21) is enabled on both the printer and the network, and

  • Access controls are not limiting FTP function.

Markvision Enterprise


Download the latest User's Guide and perform a search on Print Server updates or Generic File downloads.

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How to check printer firmware levels

To do this, obtain the Menu Settings page or access the printer's embedded web server (EWS) for this purpose. 

Checking firmware levels via Printer Menu's Setting page


Touch Settings.


Touch Reports.


Touch Menu Settings Page to start printing.


Look for the code level under “Device Information”. 


Checking firmware levels via the printer's embedded web server (EWS):


Launch your internet browser application.


After http://, enter the printer's IP address.


Click on Reports.


Click on Device > Device Information.



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