840T654dn

Lexmark T654dn error 840: Tray communication fault

The Lexmark T654dn error 840 is a service code indicating a communication fault with a paper tray. This occurs when the printer fails to identify the installed tray due to an electrical connection error. If you are asking what is Lexmark T654dn error 840, it is essentially a physical connection fault.

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Common causes

  • 1Dirty electrical tray contacts.
  • 2Mechanical connector misalignment.
  • 3Failed tray sensor.
  • 4Backplane communication failure.

Solutions

Quick Diagnosis

If the error appears on boot or when cycling the tray, dirty electrical pins are the most common cause.

Step-by-step Solution

  1. Remove tray: Eject the tray.
  2. Check pins: Ensure contacts are not bent.
  3. Cleaning: Use compressed air in the bay.
  4. Reseat: Reinsert the tray to verify engagement.

Prevention and Maintenance

Clean the tray area monthly. Avoid slamming the tray shut.

When to call a technician

If cleaning the pins fails, the internal sensor board may be dead.

Equipment Technical Data

  • Technology: Monochrome Laser
  • Speed: 55 ppm
  • Connectivity: Ethernet, USB
  • Capacity: 650 sheets standard
  • Compatible Consumables: T654 series cartridges
  • Usage: Enterprise
  • Official drivers / firmware

Steps to follow

  1. 1

    Remove tray

    Pull out the affected paper tray completely.

  2. 2

    Check pins

    Inspect the electrical contacts on the back of the tray.

  3. 3

    Reseat

    Slide the tray back in firmly to ensure a solid connection.

Frequently asked questions

It means the printer cannot communicate with the paper tray unit.

Keep connector areas clean and handle trays gently.

High-yield T654 series toner cartridges.

Yes, if the tray cannot be detected, it will be unavailable for printing.