50.4
HP Printer
Severity: CriticalWhat Does This Error Mean?
Error 50.4 means there is a problem with the electrical circuit that powers your HP printer's fuser. The fuser is not receiving the correct voltage from the printer's power supply. This is a critical error that often requires a new fuser or power supply unit.
Affected Models
- HP LaserJet Pro M400 Series
- HP LaserJet Enterprise M600 Series
- HP LaserJet Enterprise 4250
- HP LaserJet Pro MFP M428
- HP Color LaserJet Enterprise M554
Common Causes
- The fuser's electrical connector is not fully seated, causing an intermittent or missing power connection
- The printer's internal power supply unit (PSU) is failing and no longer delivering correct voltage to the fuser
- The fuser unit itself has an internal short circuit or failed heating element
- Voltage spikes from the wall outlet damaged the printer's power supply or fuser circuit
- The formatter board has a fault that prevents it from properly controlling the fuser power circuit
How to Fix It
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Turn the printer off and unplug it from the wall. Wait 30 minutes for everything to fully cool and discharge.
Electrical components inside the printer can hold a charge briefly after power is removed. Waiting 30 minutes is a safe precaution.
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Remove the fuser unit. Inspect the electrical connector on the fuser and the corresponding connector on the printer body.
Look for bent pins, burn marks, or debris in the connector. A bent pin is often the sole cause of a 50.4 error.
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Gently clean both connectors with a dry cotton swab. Straighten any bent pins carefully with a toothpick.
Do not use water or liquid cleaners on electrical connectors.
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Reinstall the fuser firmly, ensuring both side connectors click fully into place. Plug the printer into a different wall outlet — not a power strip.
Power strips can limit current delivery and sometimes contribute to fuser circuit errors.
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Power on the printer and observe the startup. If error 50.4 persists, the fuser or power supply unit needs to be replaced.
Try replacing the fuser first — it is cheaper. If the error continues with a new fuser, the PSU is the likely culprit.
When to Call a Professional
Error 50.4 is a critical electrical error. If reseating the fuser does not fix it, the power supply unit or fuser needs replacement. Formatting board repairs require professional service — contact an HP-authorized repair center.
Frequently Asked Questions
Could a power surge cause error 50.4?
Yes. Voltage spikes can damage the printer's internal power supply unit. If you experienced a power outage or storm recently, a surge may be the cause. Using a quality surge protector or UPS (uninterruptible power supply) can prevent this kind of damage.
How do I know if the fuser or the power supply is the problem?
Replace the fuser first — it is the cheaper and more common cause of error 50.4. If the error returns with a brand-new fuser installed, the power supply unit is likely at fault. A multimeter can be used to test PSU output voltage, but this is best left to a technician.
Is it worth repairing a printer with error 50.4?
If the printer is a high-volume office model, repair is usually worth it. For a low-end home printer, the cost of a new fuser plus labor may exceed the printer's value. Get a repair quote first and compare it to the cost of a replacement printer.