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- HP Community
- Printers
- Printing Errors or Lights & Stuck Print Jobs
- Re: Error code 50.4000

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10-17-2025 12:08 PM
Hello Igorkv,
Thank you for sharing your concern.
The error code 50.4000 on an HP LaserJet M402n typically indicates a problem with the fuser unit. Here are some steps you can take to resolve this issue:
Power Cycle the Printer:
Turn off the printer and unplug it from the power source.
Wait for about a minute, then plug it back in and turn it on.
Check Fuser Unit:
Ensure that the fuser unit is properly installed.
Open the printer and check for any obstructions or debris around the fuser.
Make sure the fuser is seated correctly and that all connections are secure.
Update Firmware:
Check if there is a firmware update available for your printer model. Firmware updates can sometimes resolve hardware-related issues.
Inspect Fuser for Damage:
If you are comfortable doing so, examine the fuser for any signs of visible damage or wear.
Replace the fuser if it appears damaged.
Reset the Printer:
Restore the printer to its default settings. This can sometimes clear error codes that are due to configuration issues. Refer to the printer's manual for guidance on performing a reset.
Professional Assistance:
If the error persists, it might be best to contact HP Support for further assistance, as the fuser or another internal component may need servicing or replacement.
For detailed specifications or further support, you can visit the HP LaserJet Pro M402, M403 - Printer specifications page.
Click Helpful = Yes to say Thank You.
Question / Concern Answered, Click "Accept as Solution"
10-24-2025 01:00 PM
Hello Igorkv,
Thank you for sharing your concern.
The error code 50.4000 on an HP LaserJet M402n typically indicates a problem with the fuser unit. Here are some steps you can take to resolve this issue:
Power Cycle the Printer:
Turn off the printer and unplug it from the power source.
Wait for about a minute, then plug it back in and turn it on.
Check Fuser Unit:
Ensure that the fuser unit is properly installed.
Open the printer and check for any obstructions or debris around the fuser.
Make sure the fuser is seated correctly and that all connections are secure.
Update Firmware:
Check if there is a firmware update available for your printer model. Firmware updates can sometimes resolve hardware-related issues.
Inspect Fuser for Damage:
If you are comfortable doing so, examine the fuser for any signs of visible damage or wear.
Replace the fuser if it appears damaged.
Reset the Printer:
Restore the printer to its default settings. This can sometimes clear error codes that are due to configuration issues. Refer to the printer's manual for guidance on performing a reset.
Professional Assistance:
If the error persists, it might be best to contact HP Support for further assistance, as the fuser or another internal component may need servicing or replacement.
For detailed specifications or further support, you can visit the HP LaserJet Pro M402, M403 - Printer specifications page.
Click Helpful = Yes to say Thank You.
Question / Concern Answered, Click "Accept as Solution"