Fault diagnosis
Colour prints, black does not.
One channel failing while the others work narrows things down fast — and on an inkjet it is usually the nozzles rather than the ink.
Black missing while colour works is almost always a clogged black nozzle set on an inkjet — black ink is used most and dries first. Run a nozzle check to confirm. On a colour laser it usually means the black cartridge is empty, not seated, or its chip is not being read. Check the driver too: some settings compose black from colour inks.
Inkjet
Clogged black nozzles
The most common cause by far. Black is used on nearly every page, and pigment black in particular dries hard. Run the printer's nozzle check: it prints a pattern per channel, and gaps show exactly which nozzles are not firing.
One or two head cleans, with a nozzle check between them. Not more — see clogged nozzles.
Two different blacks
Many machines carry a pigment black for text on plain paper and a photo black for glossy media. If text is missing but photos look fine — or the other way round — the machine may be selecting the channel that is clogged. The media setting in the driver decides which one is used.
Cartridge seated or recognised
Reseat the black cartridge and clean its contacts. A cartridge the machine cannot read is a cartridge it will not print from.
Colour laser
Black in a colour laser is a separate cartridge and drum, so it fails independently.
- Empty — black is consumed fastest in most offices
- Not seated properly — remove and refit firmly
- Chip not read — clean the contacts on cartridge and machine
- Its drum has failed — where drums are separate per colour
Check the driver before the hardware
Two settings cause this and neither is a fault:
- Composite vs true black. Some drivers build black from cyan, magenta and yellow. If your colour channels are low, that "black" comes out muddy or missing.
- Greyscale or black-only mode left switched on can make colour appear to fail instead.
Print the machine's own self-test from its panel. If black prints there but not from your computer, it is the driver, not the printer.
Common questions
Why does my printer print colour but not black?
On an inkjet, nearly always clogged black nozzles — black is used most and dries first. Run a nozzle check to confirm before replacing anything.
The black cartridge is new and it still will not print.
Check it is seated and its contacts are clean, and check the driver is not composing black from colour inks. If the self-test page prints black, the fault is on the computer side.
Black text is missing but black in photos prints fine.
Your machine likely has two blacks — a pigment black for plain paper and a photo black for glossy. The one used for text is clogged. The media setting decides which is selected.
How many head cleans should I run?
Two at most, with a nozzle check between. Each cycle uses a lot of ink, and a hard-dried head needs soaking rather than more cycles.
Tell us what it is doing.
Call and describe the make and the symptom — most jobs are done in a single visit, and we will tell you straight if it is not worth repairing.