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Lexmark T640

Lexmark T640

902.29 Service Engine error

What you will see

The printer displays a 902.29 Service Engine Comm error and stops working.

Recommended actions



If this is the first time that you have seen this error on the printer, power it off and let it sit for one minute. Then power it back on. If the printer returns to the 'Ready' status, try printing again to see if this has corrected the issue.

NOTE: If the printer works correctly, continue normal usage. Pay close attention to the printer for the next few days, however, to see if the error returns.


If the 902.29 error returns on power-up or during operation, the toner cartridge may be malfunctioning.

  1. Make sure the installed toner cartridge is an original Lexmark brand cartridge. If it was manufactured, refilled, or refurbished by someone other than Lexmark, please replace it with an original Lexmark product.

  2. If an original Lexmark brand toner cartridge is installed, power off the printer and replace the cartridge using one of the methods below. IMPORTANT! Make sure that the printer is powered off when changing the toner cartridge, or else the error will carry over to the replacement toner cartridge.

  • If you have a replacement toner cartridge in stock, replace the old cartridge with it. See if this clears the error.
  • If you have another printer of the same model, exchange toner cartridges between the two printers and see if the error follows the cartridge to the other printer. If it does, then you will need to replace the cartridge.


Power on the printer after replacing the toner cartridge. If the error continues, or if you have questions about any of these procedures, please contact Lexmark Technical Support for additional assistance. For contact information, click here.

Replacement of a defective toner cartridge

  • If a third-party cartridge is causing this issue, please contact the point of purchase to have it replaced.
  • If the cartridge has been refilled or reworked, contact the place where the cartridge was refilled to have it replaced.
  • If this is an original Lexmark toner cartridge, please contact Lexmark Technical Support. Depending on its age and usage, the cartridge may be eligible for replacement.

NOTE: If the cartridge was purchased directly from Lexmark, please contact Lexmark using the phone number or address you used to order it. If you cannot locate these, contact Lexmark Technical Support.


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