12
HP Printer
Severity: MinorWhat Does This Error Mean?
Error 12 means a door or cover on your HP printer is open. The printer will not print while any door is open — this is a safety feature. Close all doors and covers, then press Continue to resume printing.
Affected Models
- HP LaserJet 4
- HP LaserJet 4 Plus
- HP LaserJet 5
- HP LaserJet 6
- HP LaserJet 8000
Common Causes
- The top cover or output tray door is not fully closed and latched
- The rear paper access door or duplexer unit is ajar
- A door was opened to clear a paper jam and not closed properly
- Debris or a piece of torn paper is caught in a door latch, preventing it from closing
- The door sensor switch is dirty or faulty and falsely reports the door as open
How to Fix It
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Walk around the printer and check every door and cover — top, front, side, and rear. Look for any that are not fully closed.
Sometimes a door looks closed but is not fully latched. Press firmly on each door until you feel or hear it click.
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If you recently cleared a paper jam, double-check the jam access doors. These are easy to leave slightly ajar.
Some HP models have a small rear door for jam clearance that is easy to miss.
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Inspect each door latch for torn paper, debris, or anything preventing it from seating fully. Remove any obstructions.
Even a small scrap of paper caught in a latch can prevent the door from closing all the way.
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Press the Continue or Go button to clear the error once all doors are confirmed closed.
On older HP LaserJet models, the printer may resume automatically when all doors are closed.
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If the error persists with all doors closed, open and firmly re-close each door one at a time to reset the door sensor switches.
Sometimes cycling a door open and shut again resets a stuck sensor.
When to Call a Professional
Error 12 is almost always fixed by simply closing a door properly. If all doors appear closed but the error persists, the door sensor switch may be stuck or defective. A technician can clean or replace the sensor switch for $40 to $70. Contact HP Support at 1-800-474-6836 if your printer is under warranty.
Frequently Asked Questions
I closed all the doors but error 12 is still showing. What now?
Try turning the printer off, waiting 30 seconds, then turning it back on. This resets the sensor logic and often clears a false error 12. If the error appears again immediately, a door sensor switch may be faulty.
Can a paper jam cause error 12?
Yes. If paper is jammed and holding a door open even slightly, error 12 will appear. Clear any paper jam completely, then make sure all doors are fully latched. Check the rear jam access panel — it is the most commonly missed door.
Is it safe to use the printer with the toner door slightly open?
No. The printer will refuse to print if any door sensor detects an open state. This safety interlock prevents toner exposure and protects the laser assembly. Always close all doors before printing.