840.xxMS811dn

Lexmark MS811dn Error 840.xx: Jam

The Lexmark MS811dn error 840.xx refers to a paper jam specifically located in the duplex unit (double-sided printing). This error occurs when the sheet fails to correctly return to the mechanism for printing on the backside. It is vital to remove any paper scrap that may have remained hidden in the path. This model is a high-volume printer designed to last in demanding corporate environments.

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Common causes

  • 1Use of paper with too low (curves) or very high weight.
  • 2Duplex unit rollers dirty or worn from heavy use.
  • 3Paper poorly loaded in the input tray.
  • 4Paper scraps not completely removed in a previous jam.

Solutions

Quick Diagnosis

The 840.xx indicates the paper is stuck behind the fuser or in the duplex tray. If the paper tears while trying to remove it, ensure you remove all small scraps to avoid damaging the fuser.

Step-by-Step Solution

  1. Access Opening: Open the rear door of the printer where the duplex unit is located.
  2. Extraction: Pull the jammed paper gently outward following the paper path.
  3. Debris Inspection: Check the fuser area with a flashlight to ensure there are no torn paper scraps.
  4. Restart: Close all doors; the printer will detect that they have been closed and will automatically restart.

Prevention and Maintenance

Use paper weight recommended by the manufacturer. Do not overload the trays. Periodically clean the duplex rollers with a slightly damp cloth to improve traction.

When to Call a Technician

If when removing the paper you notice rollers are detached, or if the 840.xx error persists after verifying no paper is there, it is likely a sensor is broken.

Technical Specifications

  • Technology: Monochrome Laser
  • Speed: 60 ppm
  • Connectivity: USB, Ethernet
  • Input Capacity: up to 4400 sheets
  • Compatible Consumables: Lexmark 52D/62D cartridges
  • Recommended Usage: Heavy corporate printing
  • Official Drivers / Firmware

Frequently asked questions

It is a specific duplex unit jam code, indicating that the paper has become stuck during double-sided printing.

Generally not, it only requires opening the rear door and removing the jammed paper, being careful not to tear it.

Poor quality paper or incorrect grammage are usually the culprits of duplex jams.

If jams are frequent, cleaning the feed rollers with a damp cloth can help.

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