Don’t you hate having to replace the toner cartridge, especially when the printing seems to be fine? Surely, there must be more life in the toner.
Well, here’s a workaround in the spirit of responsible consumption: use up what you have fully to reduce waste, and, in this case, save money.
The tip is from a forum topic from fixyourownprinter.com and focuses on Brother printers, though I suspect it would work on other printers, too. You could get another 500-1000 pages printed, as reported by some on the forum.
The printer decided it was out of toner, even though the last page printed was fine. Rather than run out for a new toner cartridge I used a small (.5 x .5 in.) piece of black electrical tape to cover the sensor hole on the non-gear side of the cartridge. By covering the hole the printer is fooled into thinking the hopper is full of toner.
Read the full forum thread for more tips, including using masking tape and a black marker, if you don’t have black electrical tape.
Of course, I continue to advocate responsible printing, which saves paper, ink/toner and energy, which translates into $, too:

A great helpful tip!
Consumers will get extra life from a printer toner cartridge and will save a lot.
Thanks for the information.
Good tips. I was told that if you shake the printer cartridge or even better heat it gently with a hair dryer you can melt some of the ink that has dried up in the cartridge and get a few last kicks from the printer.
I have done the shaking, but I would think the hair dryer trick depends on the type of ink/cartridge. Do you have a resource on that?
I’ve an Epson printer. Heating the print cartridge gently with a hair dryer works for me. I don’t have any scientific studies on this. Sorry.