There is a whole cottage industry of "reset your HP toner" videos: cover this sensor, tape that contact, buy a chip programmer. Almost all of it is either unnecessary or harmful. This guide covers what the messages mean, the legitimate settings that control them, and why the shortcuts fail on current printers.
The messages and their legitimate fixes
| Message | Meaning | Fix |
|---|---|---|
| Toner low / Prepare new cartridge | 10–20% estimated remaining | Order a replacement; keep printing. |
| Toner very low | About 5% remaining | Set Very Low to Continue (HP) if the printer stops; replace soon. |
| Replace cartridge / Toner empty | Chip count exhausted | Install a new genuine cartridge. |
| Used cartridge installed | Chip shows prior pages | Normal if you moved it from another printer; otherwise it was refilled. |
| Non-HP / unauthorized cartridge | Chip not signed by HP | Use a genuine cartridge; see the dynamic security guide. |
| Drum unit near end of life | Separate drum counter high | Replace the drum (HP 19A/32A/120A class). |
Settings that stop the printer from nagging or stopping
HP LaserJet Pro: Setup > System Setup (or Administration) > Supply Settings > Black Cartridge / Color Cartridges > Very Low Setting: Continue. Also "Low Threshold" lets you set the percentage at which the warning appears — raise it if you want more lead time to order.
HP LaserJet Enterprise: Manage Supplies > Supply Settings, same options, plus a policy to require authorized HP cartridges.
Canon imageCLASS: Menu > Function Settings > Printer > "Action when Toner Low" or "Continue Printing When Cartridge Is Low"; and Adjustment/Maintenance > "Display Timing for Cartridge Prep." to change when the warning shows.
Why the sensor tricks fail
Older cartridges used a mechanical or optical "toner present" sensor, and covering it fooled the printer. Modern cartridges report through the chip. The chip counts pages and pixels and is signed; the printer compares the chip's history with its own. A cartridge whose chip says 100% but whose printer history says 4,000 pages is flagged as tampered. On HP printers with dynamic security that can end in "cartridge cannot be used", and there is no undo.
What a chip reset actually costs
A reset does not add toner. You get a gauge that lies until the cartridge runs dry mid-job, streaks, and a printer that has now recorded a counterfeit event. If you were going to refill, you would also need toner that matches the fuser profile — see the smearing guide for what happens when it does not. A genuine HP 85A costs a few cents per page; it is not the place to save.
Legitimate reasons a new genuine cartridge shows the wrong level
- Installed while the printer was on and the door sensor did not trigger: power cycle.
- Printer firmware older than the cartridge generation: update firmware, reinstall.
- Moved from another printer: the level shown is the true remaining level, not 100%.
- Chip contact dirty: wipe and reseat.
Reorder without the drama
The simplest way to never see a stop message: keep one spare cartridge per printer and reorder when you open the spare. For high-use models such as the HP 58A or Canon 137, a 2-pack covers roughly a year of typical office printing. Not sure which cartridge your printer needs? Use the printer cartridge finder.
Genuine cartridges mentioned in this guide
Related guides
Frequently asked questions
How do I clear a toner low message on an HP LaserJet?
Install a new genuine cartridge; the message clears on its own. To keep printing on a low cartridge, set Very Low behavior to Continue in the printer's supply settings. There is no 'reset' for the level of a genuine cartridge, and none is needed.
Do chip resetters work on HP toner cartridges?
They can trick some older printers, but current HP firmware verifies the chip's signature and page history. A reset chip is flagged as used or counterfeit, and dynamic security may block the printer. They also break the level gauge for good.
Why does my Canon printer keep saying toner low after a new cartridge?
Either the new cartridge is a refill with its original chip, or the printer needs the counter reset because the cartridge was not detected as new. Remove and reinstall the cartridge; if it is genuine and sealed the counter resets automatically.
