HP Printer Error Code 40: How to Fix It

Medium 20-45 minutes Medium Severity Verified June 2026
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Error Code
40
Brand
HP
Product Type
printer
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
20-45 minutes
HP Printer Error Code 40 indicates a bad transmission between the printer and an EIO (Enhanced Input/Output) device — typically a network card, hard disk accessory, or other expansion card installed in the printer's EIO slot. The printer detected corrupted or incomplete data during communication with that device, causing it to halt the print job. In most cases, this error can be resolved by reseating the EIO card, updating firmware, or clearing the job queue without needing professional help.
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Tools You'll Need

How to Fix Error Code 40

  1. Cancel the Current Print Job and Restart the Printer

    Do not simply put the printer in sleep mode — perform a full power cycle by turning it completely off and unplugging it from the wall for at least 60 seconds.

  2. Power Off and Reseat the EIO Card

    Always unplug the printer from the wall before touching internal components. Static electricity can damage electronic cards — if possible, touch a grounded metal surface before handling the EIO card.

  3. Check and Reseat All Cable Connections

  4. Clear the Print Queue on Your Computer

  5. Update the Printer Firmware

    Never interrupt a firmware update by turning off the printer or computer. Doing so can permanently damage the printer's software, requiring a service center repair.

  6. Update or Reinstall the Printer Driver

  7. Test with the EIO Slot Empty (If Possible)

    Removing the EIO card will disable any functionality it provides, such as network printing. Only do this as a diagnostic test.

  8. Replace the EIO Card If Faulty

    Purchase only cards confirmed compatible with your specific HP printer model. Installing an incompatible EIO card can cause additional errors.

Parts You May Need

EIO network card
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EIO hard disk accessory
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Ethernet cable
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EIO slot blank cover plate
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EIO network card
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EIO hard disk accessory
Check Price on Amazon
Ethernet cable
Check Price on Amazon
EIO slot blank cover plate
Check Price on Amazon
EIO network card
Check Price on Amazon
EIO hard disk accessory
Check Price on Amazon
Ethernet cable
Check Price on Amazon
EIO slot blank cover plate
Check Price on Amazon
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When to Call a Professional

Contact an HP-authorized service technician if Error Code 40 persists after reseating the EIO card, updating firmware, clearing the print queue, and replacing the EIO card. You should also seek professional help if you notice physical damage to the EIO slot itself (bent pins, burn marks, or cracked housing), if the printer displays additional error codes alongside Error 40, or if the printer is under warranty and you want to avoid voiding it by opening internal components. HP support can be reached at 1-800-474-6836, and HP's website offers chat-based and paid remote support options.

Frequently Asked Questions

What does Error Code 40 mean on an HP printer?
Error Code 40 on an HP printer means the printer detected a bad or failed data transmission with an EIO (Enhanced Input/Output) device installed in the printer's EIO slot. This could be a network card, hard disk, or other accessory. The printer stops the print job to prevent corrupted output.
Can I fix HP printer Error Code 40 without removing the EIO card?
Yes, in many cases you can fix it without physically removing the card. Start by power cycling the printer, clearing the print queue, and updating the firmware and drivers. These software-level fixes resolve Error 40 in a significant number of cases. Only remove or replace the EIO card if the error persists after all software steps are exhausted.
Why does HP Error Code 40 keep coming back?
If Error 40 keeps recurring, the most likely causes are a failing or incompatible EIO card, a damaged EIO slot on the printer's motherboard, corrupted firmware, or a persistent problematic print job being resent from your computer. Try replacing the EIO card first; if the error continues without the card installed, the EIO slot itself may be damaged and requires professional repair.
Does HP Error Code 40 mean my printer is broken?
Not necessarily. Error Code 40 is a medium-severity error related to the EIO accessory communication, not the core printing mechanism. Most printers displaying this error can be fully restored to working order by reseating or replacing the EIO card and updating firmware. The base printer hardware is usually unaffected.
What is an EIO card in an HP printer?
EIO stands for Enhanced Input/Output. It is a proprietary HP expansion slot found on many LaserJet and enterprise-class printers that allows add-on accessories to be installed, such as a JetDirect network card for wired or wireless networking, an additional hard disk for storing fonts and forms, or other communication cards. The EIO slot provides high-speed data communication between the accessory and the printer's main processor.

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