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Lexmark Printer Error 900 – Meaning, Causes & Fix

LexmarkPrinterUpdated 2026-09-24

Error 900 on a Lexmark printer is a general microcode or service-required error indicating that the printer's main controller board has encountered an unexpected condition that it cannot recover from on its own. Unlike more specific error codes (such as paper jam or toner low codes), Error 900 is a broad controller-level fault that can be caused by firmware corruption, a hardware fault on the main board, a print job that contains data the controller can't process, or a power supply irregularity. This error appears across Lexmark's monochrome and color laser printer lines, including the MX, MB, and CS series. This guide explains what triggers Error 900 and how to resolve it. For related printer controller-level errors, see our Epson Printer Recovery Mode guide and our Ricoh Printer SC542 Error guide.

Quick Answer

What it means

The printer's main controller board has encountered an unexpected microcode or hardware condition it can't recover from — most commonly due to firmware corruption, a main board hardware fault, a problematic print job, or a power supply irregularity.

Severity

High

Can you fix it yourself?

Partially — a power cycle and print queue clearing are DIY, but a persistent Error 900 typically requires firmware reflashing or main board service.

Call a technician when

Contact Lexmark support if Error 900 recurs after a power cycle and clearing the print queue, as this indicates a firmware or main board hardware fault requiring professional service.

What Does 900 Mean?

Lexmark printers use a numeric error code system where low numbers (2xx, 3xx, 9xx) identify specific subsystem faults. Error 900 is a general controller-level fault — it indicates that the main controller board (the system board that runs the printer's firmware and processes print jobs) has encountered an unexpected condition that the firmware can't handle, and the printer has halted to prevent data corruption or hardware damage.

Common causes include:

1. Firmware corruption: The printer's firmware has become corrupt — often from a power interruption during a firmware update or a failing flash storage chip. 2. Problematic print job: A print job containing malformed data, a corrupt font, or an incompatible page description language (PCL vs PostScript) can overwhelm the controller and trigger Error 900. 3. Main board hardware fault: A failing component on the main controller board (a bad memory chip, a failing processor, or a failing I/O controller) causes intermittent controller faults. 4. Power supply irregularity: Voltage fluctuations from a failing power supply or an overloaded wall circuit can cause the controller to crash. 5. Memory upgrade issue: A faulty or incompatible memory module installed in the printer causes controller errors. 6. Network card fault: A failing network interface card or a network loop flooding the printer with malformed packets triggers the controller fault.

This controller-level fault is conceptually related to the Epson printer Recovery Mode condition, which also reflects a firmware or controller-level issue rather than a consumable or paper-feeding fault.

What Causes This Error?

  • Firmware corruption from a power interruption during a firmware update or a failing flash storage chip
  • Problematic print job containing malformed data, a corrupt font, or an incompatible page description language (PCL vs PostScript)
  • Main board hardware fault — a failing memory chip, processor, or I/O controller on the main controller board
  • Power supply irregularity — voltage fluctuations from a failing power supply or an overloaded wall circuit
  • Faulty or incompatible memory module installed in the printer
  • Failing network interface card or a network loop flooding the printer with malformed packets
  • Excessive ambient temperature causing the controller to overheat and crash during heavy printing

How to Fix 900

  1. 1

    Power cycle the printer. Turn the printer off, unplug the power cord from the wall outlet, wait 60 seconds, plug it back in, and turn the printer on. A single transient Error 900 often clears with a power cycle and doesn't recur.

  2. 2

    Clear the print queue on the host computer. If the Error 900 appeared immediately after sending a specific print job, the job may contain malformed data. Cancel all pending print jobs in the Windows or macOS print queue, then resend the job after the printer recovers.

  3. 3

    Try printing from a different application or file. If the error recurs only with one specific document, the document likely contains a corrupt font, image, or page description the controller can't process. Re-create the document or print it as a PDF, which uses a more controlled page description.

  4. 4

    Verify and reseat any installed memory upgrades. If a memory module was recently added, power off the printer, remove the memory module, and test the printer without it. If the error clears, the memory module is faulty or incompatible and should be replaced or removed.

  5. 5

    Plug the printer into a different wall outlet. If the printer shares an outlet with a heavy-draw device (heater, copier, laser printer), move it to a dedicated outlet to rule out a power supply irregularity causing the controller to crash.

  6. 6

    Contact Lexmark support if Error 900 recurs. If the error returns after a power cycle, queue clearing, and memory verification, contact Lexmark support. A recurring Error 900 typically indicates firmware corruption (requiring a reflash) or a main board hardware fault (requiring service or board replacement).

When to Call a Professional

If Error 900 recurs after a power cycle, print queue clearing, and memory verification, contact Lexmark support. A firmware reflash (sometimes performed remotely by Lexmark support) can resolve firmware corruption, but a confirmed main board hardware fault typically requires a service visit and board replacement — on out-of-warranty printers, this often approaches the cost of a replacement printer. Lexmark support can run remote diagnostics to distinguish firmware corruption (reflashable) from a hardware fault (requiring service).

Can You Still Use the Device?

A Lexmark printer displaying Error 900 cannot print until the controller fault is resolved, so pending print jobs will queue but not complete. A single transient Error 900 often clears with a power cycle and doesn't recur, but a recurring Error 900 indicates a deeper firmware or hardware fault that must be addressed before reliable printing can resume.

Official Resources

Disclaimer: This article is for informational purposes only and does not constitute professional repair advice. CodeExplain is not affiliated with Lexmark or any other brand mentioned. Always consult a qualified technician for complex repairs.