HP F8100 Showing “E” Error on Refilled Black Cartridge? Here’s What It Means and How to Fix It

Question:

My HP F8100 printer is no longer recognizing my refilled HP 21 black cartridge. It initially worked, and my refilled color 22 cartridge is still fine. But now, the black cartridge triggers an “E” error. When I remove the black cartridge, the “E” goes away, and the printer even feeds paper for a test page with just the color cartridge. I’ve refilled this cartridge many times before without issue. Is it now defective and needs replacing?

Answer:

Understanding the "E" Error on the HP F8100 with Refilled HP 21 Cartridges

The “E” error code on your HP F8100 typically points to an issue with cartridge recognition. In your case, the fact that the error only appears when the refilled HP 21 black cartridge is installed, while the HP 22 color cartridge still works fine, strongly suggests the issue lies with the black cartridge itself.

Step-by-Step Troubleshooting

1. Clean the Contacts on Both Cartridge and Printer

Sometimes, the issue is as simple as a poor electrical connection between the cartridge and the printer’s contact pins.

• Remove the black cartridge.

• Inspect the gold contact points (the copper-colored ribbon).

• If you see any dried ink, oil from your fingers, or adhesive residue, gently clean the contacts with a lint-free cloth or paper towel lightly dampened with isopropyl alcohol.

• Also, inspect the contact pins inside the cartridge holder on the printer. Make sure they are not bent, and that no moisture or ink buildup is present.

• Re-insert the cartridge several times to help reseat the contacts and ensure proper alignment.

If, after doing this, the “E” error persists, the cartridge may have failed electronically.

2. Why Refilled Cartridges Can Suddenly Fail

It’s important to understand that HP 21 and 22 cartridges contain built-in circuitry and thermal resistors. These components are tested every time you install or run a print job.

Here’s what happens:

• The printer sends voltage to a reference resistor inside the cartridge.

• It compares this to the resistance values across all the ink nozzles.

• If the printer detects too many failed nozzles—where the resistance readings are outside an acceptable range—it will mark the cartridge as defective.

• The error code cannot be reset or bypassed in most HP Deskjet models like the F8100.

In your case, the black cartridge has likely exceeded HP’s built-in failure threshold. This is common with older cartridges that have been refilled 6–8 times (as you mentioned) or have been stored for long periods. Heat and usage gradually degrade the nozzle integrity, even if the cartridge was refilled carefully.

Cartridge Replacement: What to Buy and What to Avoid

If you decide to replace the cartridge, be selective—not all “new” or “refilled” cartridges are created equal.

Recommended:

• Search online marketplaces like eBay for “empty virgin HP 21 cartridge.”

  • “Virgin” means the cartridge has never been refilled before, so its internal sensors haven’t been overused.

  • These are ideal for DIY refilling.

Avoid:

• Remanufactured or cloned cartridges. These often have aftermarket chips or altered firmware that can cause recognition issues, especially if moisture gets into the contacts.

• Used OEM cartridges that don’t specify “virgin.” These may already be flagged as bad or may have degraded nozzles.

Final Thoughts

Unfortunately, once the printer decides a cartridge has exceeded its usable limits, it won’t recognize it, even if you’ve cleaned, refilled, and reinstalled it perfectly. Given the age and refill history of your black cartridge, it’s very likely that the internal components have reached their end of life.

Printer Repair and Support Options

Addressing printer problems like these can be tricky due to the hands-on nature of the hardware. As such, we’re unable to offer remote diagnosis or repair support. However, we do offer in-person repair services at our diagnostic center:
Printer Repair Service
(https://bchtechnologies.com/printer-repair-service)

We operate on a first-come, first-served basis, so there may be a waiting period before your printer is evaluated. Our services range from full-unit repairs to targeted board or cartridge port diagnostics. That said, our service may not always be the most cost-effective, especially for older or budget printers.

For DIY enthusiasts, we highly recommend leveraging free resources online, particularly our YouTube channel (https://youtube.com/@bchtechnologies). Use the search icon next to the “About” tab to quickly find videos by keyword, such as “HP 21 cartridge error” or “clean cartridge contacts.” With over nine years of content, there's a strong chance you’ll find a solution faster through targeted searching.

Thank you again for contacting BCH Technologies. We appreciate your patience and your trust, and we hope your printer gets back up and running soon.