1688 is a support code documented for Canon PIXMA TR4720, Canon PIXMA TR4722. The printer has detected an empty cartridge.
What this support code means
The printer has detected an empty cartridge.
Applies to: Canon PIXMA TR4720, Canon PIXMA TR4722. Do not reuse the same code on an unrelated model.
What to try, in order
- Replace the indicated cartridge with the correct US part.
- Optional only: the model manual describes holding Stop for at least five seconds to disable ink-level monitoring and continue when residual ink remains. This is not a refill or a repair.
After each step, repeat the action that produced the message. If it clears, you can stop.
Does this call for a replacement?
The cited model procedure calls for replacement when this exact message is present. Confirm the full model, component type and current US part list; toner, drum and maintenance boxes are not interchangeable.
Part pages contain paid Amazon search links only after the diagnostic context; no seller or retail item is verified by this error code.
When to stop
Stop if the instructed check does not apply, access requires disassembly, or the error persists after the documented steps.
- Disabling ink monitoring does not restore ink; output can deteriorate. Keep this optional and never auto-select it.
If this exact message calls for replacement, verify the current OEM part number and seller before ordering.
Models covered by this source
Official sources
These links identify the source and its scope. Check the manufacturer page again before changing a printer setting or buying a part.
- Canon — TR4700 series support code 1688 Checked 2026-11-01; official full page
Useful next steps
Found a mismatch? Request a correction with the public source URL and exact model, without passwords or full serial numbers.