HP Printer Error Code 46 — What It Means & How to Fix It

What Does This Error Mean?

Error 46 on HP LaserJet printers indicates a failure in the printer's input/output (I/O) system. This usually means the printer cannot communicate properly with an accessory or card installed in one of its expansion slots. It can also occur when the printer's communication with a connected computer breaks down at a hardware level.

Affected Models

HP LaserJet 4000 Series
HP LaserJet 4050 Series
HP LaserJet 5000 Series
HP LaserJet Enterprise M600 Series
HP LaserJet Pro M700 Series

Common Causes

An EIO (Enhanced Input/Output) card — such as a network card or print server — is failing or seated incorrectly
The EIO card installed in the printer is not compatible with the current firmware version
Dust or debris on the EIO card contacts is causing a poor electrical connection
The printer was powered off during a firmware update, corrupting the EIO interface firmware
A defective or failing formatter board is unable to communicate with the installed EIO card

How to Fix It

Turn off the printer and unplug it from the wall. Wait 60 seconds before continuing.

Never remove or insert EIO cards while the printer is powered on — you can permanently damage both the card and the printer.
Open the printer's rear access panel and locate any EIO cards installed in the expansion slots. Remove each card carefully.

EIO cards are held in place by screws. Keep track of which card was in which slot if you have more than one.
Inspect the gold contacts on the bottom of each EIO card. Clean them gently with a pencil eraser to remove oxidation, then wipe away eraser debris with a lint-free cloth.

Oxidized or dirty contacts are a very common cause of I/O communication errors.
Reseat each card firmly into its slot and secure the screws. Power the printer back on and check if the error is gone.

Try the printer with only one EIO card at a time if you have multiple installed — this helps identify which card is causing the problem.
If the error returns, update or reinstall the printer firmware. Visit support.hp.com, find your model, and download the firmware update package.

A fresh firmware install can resolve compatibility issues between the printer's main board and the EIO card.

When to Call a Professional

If error 46 persists after removing and replacing the EIO card, and a firmware reinstall does not help, the formatter board or EIO slot itself may be damaged. Have an HP-certified technician inspect the internal hardware. Repair costs vary but formatter board replacement typically runs $80 to $180.

Frequently Asked Questions

What is an EIO card and do I need one?

EIO stands for Enhanced Input/Output. It is an expansion card that adds features to HP LaserJet printers — the most common type is a Jetdirect network card, which lets the printer connect directly to a network without going through a computer. If you are not using a network card or other EIO accessory, you do not need one, and removing it will eliminate this error source entirely.

Can error 46 appear even without an EIO card installed?

Yes, though it is less common. If no EIO card is installed, the error may indicate a fault on the formatter board itself — specifically the circuitry that manages I/O communication. In this case, a formatter board replacement is the likely fix.

Will replacing the EIO card fix error 46 for sure?

If the card itself is faulty, yes — a replacement card of the same model should resolve the error. However, if the EIO slot on the formatter board is damaged, a new card may still fail. Testing with a known-good card first (borrowed from another printer if possible) is the best way to confirm whether the card or the slot is the problem.