The colour toner cartridges yield up to 6,000 pages when printing at 5% coverage on A4/ Letter sized paper. When one of the toner cartridges begins run out, the message 'Replace xxxx Toner (x)' message appears on the operation panel (xxxx is the toner cartridge colour). Replace the toner cartridge(s) as soon as the message prompting you to do so appears. The printer will stop operating if you do not replace the toner cartridge when required.