Printer Faults - Print Cartridge Light

The print cartridge light means the printer is running out of toner - or thinks it is

On older printers there might be a sensor for the cartridge toner level such as a light beam or a current detector on the stirring paddles. On recent printers those things migh exist but cartridge exhaustion might actually be calculated rather than sensed. Software in the printer works out how much toner a page took and then writes a new value for the remaining toner into a chip carried on the cartridge.

If a cartridge is anything other than a pristine manufacturers original then the toner low light may be wrong.

Toner detectors don't always get things right because toner can be heaped at one side of the cartridge. User guides often recommend holding the cartridge horizontally and shaking it from side to side to even out the toner.

Some modern laser printers are designed to have "no shake" cartridges where the stirrer blades will even out any imbalance of toner inside. The manual may recommend against shaking cartridges. Generally there is no harm in shaking a cartridge (after all it gets tipped every which way in shipment. The problem is that a shaken cartridge can make a mess on the user's clothes and carpets - so be careful. If you feel that the light is lying and there should be toner in the cartridge, shake it over Lino or a sink and keep it away from your clothes. Or see the section on cleaning up here

How long toner will last is a matter of how big the cartridge is and how much you use the printer. The smaller printers that have lights as indicators tend to have cartridges rated for as few as 1,500 to 2,500 pages at 5% cover. To put this in perspective, many households print as few as two pages per day so that can allow several years of use.

By contrast business users in something like a purchasing office might print a page with every order so their consumption could well exhaust a cartridge in a week. Small cartridges tend to be quite costly per copy, so a bigger printer with more cost effective cartridges might pay for itself in a year.

Warning lights that don't seem sensible can also be a warning that something problematic has happened. For instance if the "attention" light is also on the pair of lights together may mean something like "fuser fault".

Obscure light messages have to be looked up in the user guide. If you don't have the user manual (in a heap of discarded CDs) search engines are often helpful. A phrase such as -

• "aculaser C900" "reference guide" filetype:pdf
• "Laserjet CM4540" "user guide" filetype:pdf

Some manufacturers are more benevolent than others in making user manuals easy to find online.