HP Error 51: Internal hardware error
Also shows as: 51.XX Error, 51.XY Error, Turn off then on
🧑🔧 Needs servicing
The printer has had an internal hardware error. On older models HP describes it as a temporary printing error.
What to try
- Turn the printer off, wait at least 30 seconds, then turn it on and let it initialize.
- If you use a surge protector, remove it and plug the printer directly into the wall outlet.
- Turn the printer on again and check whether the message clears.
When it needs a technician
If the message persists, HP says to contact HP support.
Which models show 51
HP documents this code for models including HP LaserJet Pro 400 M401, HP LaserJet Pro M701/M706, HP LaserJet P2050 series, HP LaserJet P3010 series.
First steps for any printer error
- Write down the exact code before you do anything else — similar-looking codes often mean completely different things.
- Power the printer off, unplug it for a couple of minutes, then power it back on. A surprising number of transient errors clear here.
- Open the covers and check for paper scraps, packaging material, or anything blocking the carriage.
- Check the cartridges or tanks are genuine, correctly seated, and not empty.
- Confirm the printer is plugged directly into a wall outlet, not a power strip or extension lead.
- Check your model’s own manual — codes are model-specific, and the manual is the authority for your machine.
Source: HP Customer Support - HP LaserJet Pro 400 Printer M401, Interpret Control Panel Messages. Codes are model-specific, so your own model's manual is the final word. Reviewed October 2026.
Still showing 51?
Tell our printer technician your model and what you've tried. You'll find out whether it's fixable at home or worth repairing at all.
Ask about my printer — $1Eric Paul Amora · Printer & Hardware Repair Technician
Related HP codes
79 — Internal firmware error49 — Firmware communication error50 — 50.x fuser error52 — Laser scanner error54 — Internal sensor error55 — Internal engine error57 — 57 fan error59 — Motor error10.0000 — 10.x supply memory error (toner cartridge)13 — 13.XX paper jam20 — 20.xx memory out error21 — 21.xx print failure