Fault diagnosis
Plugged in, powered on, invisible.
A printer the computer cannot see is usually a cable, a port or a driver — and there is a quick way to tell which.
First establish whether the printer itself is healthy: print a self-test page from the printer's own panel. If that works, the machine is fine and the problem is the connection or the driver. On USB, try a different cable and a port directly on the computer rather than a hub. On network, confirm the printer has an IP address.
Self-test first
Print the configuration or self-test page from the printer's panel. It takes seconds and tells you whether you are debugging a printer or debugging a computer. If it prints, the printer is fine.
USB
The cable
USB printer cables fail more often than people expect, especially where they get moved or pinched. A cable that charges a phone is not proof — data and power are different pins. Swap it for a known-good one.
The port
Plug directly into the computer, not a hub, not a monitor, not a dock. Printers draw and negotiate differently from other devices and are fussier about intermediaries. Try a different port; try a rear port on a desktop rather than a front one.
Cable length
USB has real length limits. A long cheap cable, or a run of extensions, causes intermittent detection that looks like a printer fault.
Driver installed in the wrong order
Many manufacturers want the driver installed before the printer is plugged in. Doing it the other way round can leave Windows holding a generic driver that never quite works. Uninstall, then reinstall in the documented order.
Network
- Print the network configuration page — does it have an IP address at all?
- If the address starts 169.254, it never got one from the router; that is a DHCP problem
- Try reaching that IP in a browser — most printers have a web interface. If it loads, the network is fine and the problem is on the computer.
- Check the printer is on the same network, not a guest network
That browser test is the single most useful thing you can do: it separates network problems from driver problems in about ten seconds.
Windows specifics
- Check Device Manager for an unknown device appearing when you plug in — that means it is seen but has no driver
- Remove old copies of the printer that have accumulated in Settings
- Restart the Print Spooler — see printer offline
- After a major Windows update, reinstall the manufacturer's driver
When it is the printer
If the self-test will not print either, or nothing lights up, the fault is in the machine — power supply, formatter board or panel. That is a bench job.
Common questions
My computer cannot find my printer over USB.
Try a different cable and plug directly into the computer rather than a hub. Then check whether the driver was installed in the order the manufacturer specifies — many want it installed before you plug the printer in.
How do I know if the printer or the computer is at fault?
Print a self-test page from the printer's own panel. If it prints, the printer is fine and you are debugging the connection or the driver.
The printer has an IP starting with 169.254.
It never received an address from the router. That is a DHCP or network problem rather than a printer fault — check the cable or the Wi-Fi connection.
Can I test a network printer without a driver?
Yes. Type its IP address into a browser. Most printers have a built-in web interface, and if it loads, the network path is fine and the problem is the driver.
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.