Canon · Ink / cartridge
Canon PIXMA Support Code 1688
Canon's TS3600-series documentation says 1688 means the printer has detected one or more empty ink cartridges.
Start hereThe normal fix is to replace the indicated empty cartridge. Some Canon models also document a Stop-button procedure that disables remaining-ink detection, but only use that option if your exact model's manual says to.
What to check
Step 1
Identify which cartridge the printer reports as empty.
Open the cover only as directed for your model.
Step 2
Replace the empty cartridge for normal operation.
Canon recommends a new cartridge for normal image-quality and ink-level monitoring.
Step 3
If you intend to continue with residual ink, check your exact model manual first.
On the cited TS3600 series, Canon documents holding Stop for at least five seconds to disable remaining-ink detection.
Step 4
Expect limitations when ink detection is disabled.
The printer can no longer reliably report remaining ink for that cartridge.
Verified sources
Printer Triage is an independent troubleshooting reference and is not affiliated with Canon. Use the exact model's manufacturer documentation when instructions differ.