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Clearing the 5B00 "ink absorber full" error

For owners of a Canon G-series MegaTank (G6020 and relatives) stopped with support code 5B00. No reverse-engineering background assumed — for the protocol and the engineering, see the field guide and the validated runbook.

Install a waste-ink pad kit first

5B00 means the waste-ink absorber counter has reached its limit. Resetting a physically full absorber overflows ink inside the printer. Install a fresh absorber/maintenance kit before resetting, and reset only printers you own.

What 5B00 is

A counter in the printer's memory — not a broken part. Firmware refuses to print once it crosses a threshold, and this generation's consumer firmware exposes no user reset. This tool performs the service-mode reset over USB.

What you need

  • The printer, with a fresh waste-ink absorber kit installed.
  • A Linux computer and a USB cable.
  • Comfort running one terminal command.

A signed graphical macOS/Windows/Linux app is tracked as a community contribution in issue #31; until it lands, the steps below are the supported path.

Steps

  1. Install the absorber kit (see the warning above) — do not skip this.
  2. Enter service mode. Power off. Hold ON, press Stop/Resume five times, then release ON. The screen turns to a plain colour field.
  3. Connect the printer to the Linux computer by USB.
  4. Run the tool (install per the README): 
    canon-megatank reset-native            # dry run — prints what it will do, writes nothing
canon-megatank reset-native --execute  # performs the reset
    It refuses to run against the wrong printer and snapshots the printer's memory first.
  5. Power-cycle with the power button. Let the tool finish, then turn the printer off with its power button (not by unplugging) — you will hear the printhead park. Turn it back on.
  6. Done. The printer returns to normal mode and prints.

If it does not clear

  • Confirm you used the power button, not the plug — the reset commits during a clean shutdown.
  • Confirm the printer was in service mode (plain-colour screen) when you ran the tool.
  • See the troubleshooting section of the runbook.

Is this allowed?

Resetting your own printer's waste-ink counter, after installing fresh pads, is a repair — not a circumvention of any content protection. See right to repair.