How to Fix Epson WF-3640 0x9A Error After Printhead Replacement: What It Really Means

Customer Question 

Thank you for the video on how to change the printhead on the Epson WF-3640. I just installed a new printhead, but now I’m getting an error code 0x9A. Does this mean the new printhead is faulty?

Watch the original video and comment.

Answer

What Does the Epson 0x9A Error Code Mean?

The 0x9A error on Epson WF-series printers typically refers to a general hardware failure, and it often comes up after replacing a printhead. While a faulty new part can sometimes trigger it, it’s more commonly related to an underlying electrical issue on the mainboard, particularly:

Blown Fuse on the Mainboard

When the original printhead fails—mainly due to an internal short—it can burn out the head driver circuit or fuse on the main logic board. Unfortunately, when you install a new printhead, the printer still cannot drive it correctly if the power line is dead. That’s when the system throws a 0x9A error.

This means:

• Your original printhead might have damaged the board.

• The new printhead may not be faulty—but it cannot operate due to a power delivery problem.

Let’s Talk About Replacement Printhead Quality

If your new printhead came from a low-cost source (typically under $50 on Amazon or AliExpress), then yes—it could very well be a fake or defective unit. These listings often sell what looks like a new printhead, but the product either:

• Has been salvaged and poorly reconditioned,

• Has fake circuitry or mismatched resistance profiles,

• Or is it an outright scam that doesn't function at all?

Genuine Epson F198000 (WF-3640 printhead model) parts typically retail well above $100 unless you’re buying used, which comes with its risks.

What You Should Do Next

1. Inspect the Mainboard Fuse

   • If you're comfortable opening the printer, you can check the mainboard for tiny surface-mount fuses near the printhead cable connector.

   • If the fuse is blown (no continuity), that’s likely the reason the printer cannot drive the head anymore.

   • These fuses are replaceable with soldering skills and the right part.

2. Test with a Verified Printhead

   • If you have access to another known-good printhead, test it before replacing the board.

   • If that head also fails with a 0x9A error, the board is almost certainly at fault.

3. Check Printhead Resistance

   • A multimeter can be used to check resistance between the head pins—bad heads often show open or shorted values.

Is the Printhead Dead on Arrival? Possibly.

The error could still point to a bad new printhead, especially if it were one of the cheaper or unbranded listings. Unfortunately, in some cases, both the printhead and the mainboard get damaged together—a cascading failure.

If your printhead came from an unreliable source and you've ruled out mainboard issues, it’s best to obtain a replacement from a verified supplier.

Final Note

Diagnosing and fixing printhead-related issues often involves both electrical and mechanical hands-on work. For that reason, we’re unable to provide remote technical support for repairs. However, we do offer in-person diagnostics and repairs at our local printer service center (https://bchtechnologies.com/printer-repair-service). Due to high demand, we operate on a first-come, first-served basis, and there might be a wait before your printer can be dropped off and assessed. Our services include full printer repairs and board-level diagnostics. If you prefer the DIY approach (which we strongly support), you can search our YouTube channel homepage (https://youtube.com/@bchtechnologies) using the search icon near the “About” tab. We’ve created a library of detailed videos over the past nine years, and YouTube may also point you toward other creators tackling similar issues.

Thanks again for being a part of the BCH Technologies community. Keep us posted—we’re here to help you get your WF-3640 back in action!