Fixing Epson WF-3640 0x9A Error After Printhead Cleaning: Causes & Repair Tips

Customer Question:

After successfully cleaning the printhead on my Epson WF-3640 using your extreme unclogging method, I now receive an error message “0x9A.” The printhead carriage won’t move, and I noticed some of the connector strips are pushed back. What could be the issue, and what did I do wrong?

Understanding the Epson 0x9A Error on WF-3640

The 0x9A error code on Epson printers—particularly in the WorkForce WF-3640 series—typically points to a carriage jam or mechanical positioning issue. However, in the context of your situation (right after cleaning the printhead and finding misaligned ribbon cables), it strongly suggests a circuit-level fault, possibly involving the mainboard fuse or carriage sensor connection.

1. Blown F1 Fuse on the Mainboard (Common Cause)

• If your original printhead was electrically damaged, reinstalling it may have caused a short circuit, which typically blows the F1 surface-mounted fuse on the mainboard.

• This fuse is responsible for protecting the printhead power circuit. When it's blown, the printer can't initialize the printhead, which often results in a 0x9A error and an unresponsive carriage.

• Solution: Open the printer, locate the F1 fuse on the mainboard (usually near the printhead connector), and test for continuity using a multimeter. If it’s blown, you’ll need to replace it with a compatible fuse or jumper it—if you're confident working at board level.

2. Disconnected or Pushed-Back Ribbon Cables

• You mentioned that some connector strips were pushed back. These flexible flat cables (FFCs) are crucial for communication between the printhead and the logic board.

• Improper or incomplete reconnection can trigger errors like 0x9A due to loss of feedback from the carriage or sensors.

• Solution: Power off the printer entirely and carefully reseat all ribbon cables going into the carriage and mainboard. Make sure they are fully inserted and aligned without crimping or damage.

3. Carriage Movement Blockage

• Although 0x9A is not typically a physical jam error (like 0x97 or 0xEA), it can still appear if the printer fails to detect proper carriage motion during startup.

• This can happen if cleaning dislodged something that now interferes with the carriage belt or rail.

• Solution: Check for any obstructions or uneven resistance in the carriage path. You may need to gently move the carriage manually (with the printer off) to verify it's free to slide.

4. Confirm Printhead Isn’t Shorting Again

• If you reused the old printhead that was clogged, it might have a shorted heating element or sensor.

• Reinstalling a damaged head after unclogging can still pose a risk to the mainboard.

• Solution: If you've replaced the fuse and continue to get errors, consider testing the board with a known good printhead before proceeding.

Additional Note

You’ve made impressive progress by cleaning the printhead successfully. This next step is about making sure all electrical connections are safe and intact. You're likely just one fuse away from a working printer again!

Addressing printer issues can be complex because they often require physical inspection and hands-on troubleshooting. As such, we’re unable to offer direct remote repair support. However, we do provide an in-person printer evaluation and repair service (https://bchtechnologies.com/printer-repair-service). Due to high demand, this service operates on a first-come, first-served basis, and it may take a few weeks before your printer can be evaluated. Our repair packages cover both complete printer diagnostics and part-specific repairs, and we provide detailed instructions for those interested. That said, we recognize that this service may not be cost-effective for everyone, so we encourage DIY approaches using available resources. You can always start by browsing our YouTube channel (https://youtube.com/@bchtechnologies) and searching using the icon near the “About” tab. With over nine years of video content, using the search bar is the fastest way to find targeted help, even if it leads to other helpful creators as well.

Thanks again for your support and your question! You're committed to maintaining your printer, and we’re here to support you every step of the way.