HP Printer Error Code 45 — What It Means & How to Fix It

What Does This Error Mean?

Error 45 on HP LaserJet printers signals an internal controller failure. The printer's main logic board detected a fault it could not recover from on its own. This is one of the more serious HP error codes and usually requires attention beyond a simple restart.

Affected Models

HP LaserJet 4Plus Series
HP LaserJet 5 Series
HP LaserJet 4000 Series
HP LaserJet Enterprise M500 Series
HP LaserJet Pro M600 Series

Common Causes

The printer's formatter board (main controller board) has a hardware fault
A memory DIMM is faulty, improperly seated, or incompatible with the printer model
An EIO (Enhanced Input/Output) card in one of the printer's slots is failing or incompatible
Static discharge damaged an internal component — common in dry environments
The printer experienced a power surge that corrupted the firmware or damaged the board

How to Fix It

Power the printer off completely. Unplug it from the wall and wait 2 minutes before plugging it back in.

Occasionally a transient electrical fault causes error 45 and a full power cycle clears it permanently.
Open the printer and locate any installed memory DIMMs. Remove each one, clean the contacts gently with a dry lint-free cloth, and reseat them firmly.

Consult your printer's manual for DIMM slot locations — on most HP LaserJets they are accessible by removing a side panel.
If any EIO cards are installed (network cards, hard disk accessories, etc.), remove them all. Power the printer on without them to see if the error clears.

EIO cards are found in expansion slots usually on the rear of the printer. A failing card can trigger error 45.
Try reinstalling the printer firmware. Download the full firmware package for your specific model from support.hp.com and apply it via USB.

Firmware corruption after a power event can sometimes produce controller-level errors. A clean firmware install may resolve the issue.
If all the above steps fail, the formatter board is likely faulty. Contact HP support or a local repair center to have it tested and replaced.

Formatter boards are model-specific — make sure any replacement is sourced for your exact HP model number.

When to Call a Professional

Error 45 is flagged as critical because it typically points to a hardware-level failure. If the steps below do not resolve it, the formatter board almost certainly needs to be replaced. HP-certified repair centers can test the board and replace it — parts typically cost $80 to $200 depending on the model.

Frequently Asked Questions

Can I fix error 45 myself, or do I need a technician?

You can try the self-service steps — reseating memory, removing EIO cards, and reflashing firmware. However, if those steps do not work, the formatter board needs to be replaced. That repair involves opening the printer and handling sensitive electronics, so most users prefer to have a technician handle it.

Is error 45 covered under HP's warranty?

If your printer is still under its original HP warranty, yes — contact HP support at support.hp.com to start a warranty claim. For out-of-warranty printers, HP offers paid repair services or you can use a third-party repair shop.

Could a bad power outlet cause error 45?

Yes, indirectly. A power surge or dirty power can damage the formatter board over time or in a single event. Using a quality surge protector (not just a basic power strip) can protect your printer from voltage spikes. If you live in an area with frequent power fluctuations, a UPS (battery backup) offers even better protection.