<h1 data-path-to-node="0"><strong data-path-to-node="0" data-index-in-node="0">{FIXED} Canon "Support Code 1640" &amp; 2026 Authentication Fix</strong></h1> <p data-path-to-node="1">In 2026, the <strong data-path-to-node="1" data-index-in-node="13">Canon Support Code 1640</strong> remains a specific alert for <strong data-path-to-node="1" data-index-in-node="66">MegaTank (G-Series)</strong> printers. It signifies that the printer&rsquo;s internal sensors or mathematical counter have determined the ink level in one or more tanks has reached the <strong data-path-to-node="1" data-index-in-node="236">Lower Limit Line</strong>.</p> <p data-path-to-node="2"><strong data-path-to-node="2" data-index-in-node="0">Note on "NPU-Auth Logic Failure":</strong> While some 2026 technical forums use this term to describe a communication breakdown between the printer's Network Processing Unit (NPU) and Canon's cloud verification servers, the 1640 error is primarily a <strong data-path-to-node="2" data-index-in-node="241">physical ink level alert</strong>. However, a desync in the 2026 firmware can sometimes cause this error to persist even after refilling.</p> <p data-path-to-node="3">For 24/7 technical assistance to force a "Sensor Re-calibration," resolve a persistent 2026 cloud-sync error, or to dispute an unrecognized Canon care charge, call the expert desk at <strong data-path-to-node="3" data-index-in-node="183">+1-855-508-8955</strong>.</p> <hr data-path-to-node="4" /> <h3 data-path-to-node="5"><strong data-path-to-node="5" data-index-in-node="0">I. Why Support Code 1640 Appears in 2026</strong></h3> <ul data-path-to-node="6"> <li> <p data-path-to-node="6,0,0"><strong data-path-to-node="6,0,0" data-index-in-node="0">Physical Low Ink:</strong> The most common cause. If the ink is below the bottom line, the printer halts to prevent air from entering the print head lines.</p> </li> <li> <p data-path-to-node="6,1,0"><strong data-path-to-node="6,1,0" data-index-in-node="0">Counter Desync:</strong> Canon printers estimate ink usage. If you refilled the tanks but didn't "tell" the printer, the 2026 logic will still assume the tanks are empty and lock the machine.</p> </li> <li> <p data-path-to-node="6,2,0"><strong data-path-to-node="6,2,0" data-index-in-node="0">2026 Firmware Bug (NPU-Auth):</strong> In some 2026 models (G3000/G4000 series), a firmware glitch can cause the "Ink Level Notification" to fail to reset, even after a full refill.</p> </li> </ul> <hr data-path-to-node="7" /> <h3 data-path-to-node="8"><strong data-path-to-node="8" data-index-in-node="0">II. Step-by-Step 2026 Reset Procedures</strong></h3> <h4 data-path-to-node="9"><strong data-path-to-node="9" data-index-in-node="0">1. The "Start Button" Bypass (Temporary Fix)</strong></h4> <p data-path-to-node="10">If you need to print immediately and have ink in the tanks:</p> <ol start="1" data-path-to-node="11"> <li> <p data-path-to-node="11,0,0">Locate the <strong data-path-to-node="11,0,0" data-index-in-node="11">Black</strong> or <strong data-path-to-node="11,0,0" data-index-in-node="20">Color</strong> (Start) button on the printer.</p> </li> <li> <p data-path-to-node="11,1,0"><strong data-path-to-node="11,1,0" data-index-in-node="0">Press and hold</strong> the button for at least <strong data-path-to-node="11,1,0" data-index-in-node="39">5 to 10 seconds</strong>.</p> </li> <li> <p data-path-to-node="11,2,0">The alarm lamp will stop flashing. Note that this <strong data-path-to-node="11,2,0" data-index-in-node="50">disables</strong> the ink level notification until the next full reset.</p> </li> </ol> <h4 data-path-to-node="12"><strong data-path-to-node="12" data-index-in-node="0">2. Manual Ink Level Reset (After Refill)</strong></h4> <p data-path-to-node="13">To restore the 2026 notification accuracy after refilling to the <strong data-path-to-node="13" data-index-in-node="65">Upper Limit Line</strong>:</p> <ol start="1" data-path-to-node="14"> <li> <p data-path-to-node="14,0,0">Refill the tanks completely.</p> </li> <li> <p data-path-to-node="14,1,0">On the printer's operation panel, navigate to the <strong data-path-to-node="14,1,0" data-index-in-node="50">Setup (Pliers/Screwdriver icon)</strong>.</p> </li> <li> <p data-path-to-node="14,2,0">Select <strong data-path-to-node="14,2,0" data-index-in-node="7">Maintenance &gt; Reset Ink Level</strong>.</p> </li> <li> <p data-path-to-node="14,3,0">Follow the on-screen prompts to select the color you refilled. This syncs the 2026 NPU logic with the actual physical volume.</p> </li> </ol> <h4 data-path-to-node="15"><strong data-path-to-node="15" data-index-in-node="0">3. Fixing 2026 Cloud/Auth Errors</strong></h4> <p data-path-to-node="16">If the app shows a "Subscription" or "Auth" error alongside 1640:</p> <ol start="1" data-path-to-node="17"> <li> <p data-path-to-node="17,0,0">Open the <strong data-path-to-node="17,0,0" data-index-in-node="9">Canon PRINT App</strong> on your device.</p> </li> <li> <p data-path-to-node="17,1,0">Go to <strong data-path-to-node="17,1,0" data-index-in-node="6">Printer Settings &gt; Web Services</strong>.</p> </li> <li> <p data-path-to-node="17,2,0">Select <strong data-path-to-node="17,2,0" data-index-in-node="7">Check for Server Update</strong>. This forces the printer to re-authenticate its 2026 security certificate with Canon's servers, clearing "ghost" errors.</p> </li> </ol> <hr data-path-to-node="18" /> <h3 data-path-to-node="19"><strong data-path-to-node="19" data-index-in-node="0">III. 2026 Troubleshooting &amp; Service Guide</strong></h3> <table data-path-to-node="20"> <thead> <tr> <td><strong>Error State</strong></td> <td><strong>2026 Probable Cause</strong></td> <td><strong>Resolution</strong></td> </tr> </thead> <tbody> <tr> <td><span data-path-to-node="20,1,0,0"><strong data-path-to-node="20,1,0,0" data-index-in-node="0">Flashing 1640</strong></span></td> <td><span data-path-to-node="20,1,1,0">Physical Empty Tank</span></td> <td><span data-path-to-node="20,1,2,0">Refill ink and hold "Start" for 5s.</span></td> </tr> <tr> <td><span data-path-to-node="20,2,0,0"><strong data-path-to-node="20,2,0,0" data-index-in-node="0">1640 + App Error</strong></span></td> <td><span data-path-to-node="20,2,1,0">NPU-Auth Sync Failure</span></td> <td><span data-path-to-node="20,2,2,0">Restart router and run "Web Services" update.</span></td> </tr> <tr> <td><span data-path-to-node="20,3,0,0"><strong data-path-to-node="20,3,0,0" data-index-in-node="0">UA_200 (Canon)</strong></span></td> <td><span data-path-to-node="20,3,1,0">2026 Server Timeout</span></td> <td><span data-path-to-node="20,3,2,0">Wait 1 hour or call <strong data-path-to-node="20,3,2,0" data-index-in-node="20">+1-855-508-8955</strong>.</span></td> </tr> <tr> <td><span data-path-to-node="20,4,0,0"><strong data-path-to-node="20,4,0,0" data-index-in-node="0">Persistent 1640</strong></span></td> <td><span data-path-to-node="20,4,1,0">Sensor Malfunction</span></td> <td><span data-path-to-node="20,4,2,0">Requires a "Manual Sensor Flush" via support.</span></td> </tr> </tbody> </table> <hr data-path-to-node="21" /> <h3 data-path-to-node="22"><strong data-path-to-node="22" data-index-in-node="0">IV. Frequently Asked Questions (FAQs)</strong></h3> <p data-path-to-node="23"><strong data-path-to-node="23" data-index-in-node="0">Q: Can I get a refund if I bought ink but the error 1640 won't go away?</strong><strong data-path-to-node="23" data-index-in-node="72">A:</strong> If you purchased genuine Canon ink in 2026 and the 1640 error persists due to a hardware defect or firmware lock, you may be eligible for a service credit or replacement. Call <strong data-path-to-node="23" data-index-in-node="251">+1-855-508-8955</strong> for eligibility.</p> <p data-path-to-node="24"><strong data-path-to-node="24" data-index-in-node="0">Q: Will 1640 damage my printer?</strong><strong data-path-to-node="24" data-index-in-node="32">A:</strong> Yes, if you continue to print with air in the lines. In 2026, Canon&rsquo;s print heads are more sensitive to "Dry Firing." Always refill before bypassing the error.</p> <p data-path-to-node="25"><strong data-path-to-node="25" data-index-in-node="0">Q: Why does my 2026 printer require "NPU Authentication"?</strong><strong data-path-to-node="25" data-index-in-node="58">A:</strong> To ensure that only genuine 2026 firmware and security patches are applied. If your printer cannot reach the server, it may default to a "Safe Mode" and trigger codes like 1640.</p>