Stop printing if the same fault returns after one careful restart or basic recovery step.
Canon / MB5400 series

B203 - The printer detected a serious print or controller fault and cannot continue normally.

The printer detected a serious print or controller fault and cannot continue normally.

This guide is scoped to the MB5400 series family. Exact menu wording, cartridge naming, and service behavior can still vary by model variant and firmware.

Severity

High

Most likely cause

A controller or print-system fault occurred.

Can you keep using it?

Usually no - see below

Consumables involved

Not usually the first suspect

Can you keep using it?

Can you keep using it?

Contact customer support if any of these apply

  • !B203 returns immediately after restart.
  • !The printer cannot reach a ready state at all.
If the printer still starts normally: Try one careful restart or the first official recovery step, then stop if the same error comes back straight away.

What to check first

Step-by-step checks

  1. 1

    Safe first step

    Turn the printer off, wait briefly, and power it back on.

    Start with the official recovery step before moving on to parts or deeper servicing.

  2. 2

    Safe first step

    Retry one short job only if the printer returns to ready.

  3. 3

    Safe first step

    Do not keep forcing repeat jobs through the same fault state.

Background

What this message usually means

Canon uses support code B203 on MB5400-series printers for a more serious printer fault that stops normal operation. It is not a low-urgency maintenance warning and usually needs a restart first, then support if it comes straight back.

Diagnosis

Likely causes

Most common

A controller or print-system fault occurred.

Common

The printer resumed from an error state and could not clear it cleanly.

Possible

A deeper internal hardware or supply-path issue stopped normal operation.

Service

When service or replacement is more likely

  • -Treat repeated B203 returns as a support case rather than a user-maintenance issue.

See also

Related codes in this family

Explore more

More Canon printer families

Keep browsing

Where to go next

Source notes

Canon's MB5400-series support-code list includes B203 in the printer fault group that stops normal operation.

Built around Canon MB5400-series support-code guidance. Exact wording can vary a little by region and model variant.

Printer error codes can vary a little by firmware, region, and exact model variant. Use this guide as a family-level starting point and stop if the next step would require disassembly or service-mode changes.

Known family variants: MB5410, MB5420, MB5440, MB5450, MB5460, MB5490

Last reviewed: 2026-04-12

Reference: Open reference

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