Epson Printer Error Code W-04: How to Fix It

Q: What is the scanner lock on an Epson printer and why does it exist?

The scanner lock is a physical mechanism — usually a switch, slider, or removable plastic clip — that locks the scanner carriage in place to prevent it from being damaged during shipping or transportation. Epson installs it at the factory before the printer is boxed. It must be unlocked before the printer can be used. If the lock is accidentally re-engaged or was never removed in the first place, the printer will display the W-04 error and refuse to operate.

Q: Where exactly is the scanner lock on my Epson printer?

The scanner lock location depends on your specific Epson model. On many Epson all-in-one printers (ET, XP, and WF series), it is found on the underside of the printer as a slide switch, or inside the scanner bed area as a removable plastic tab. The best way to find it is to download your model's user manual from epson.com/support and search for 'scanner lock' or 'transport lock.' The manual will include a diagram showing the exact location.

Q: I already unlocked the scanner but the W-04 error is still showing — what do I do?

First, make sure the switch or tab is fully in the unlocked position — partially engaged locks can still trigger the error. Then power cycle the printer by unplugging it for 60 seconds and restarting. If the error continues, open the scanner lid and check for any packing foam, tape, paper, or debris that might be physically blocking the scanner carriage from moving. If you find nothing and the error persists, the scanner carriage motor or sensor may be faulty, which requires professional service.

Q: Will the W-04 error damage my Epson printer if I ignore it?

The printer will not function at all while the W-04 error is active — it blocks all printing and scanning operations as a safety measure. You should resolve it before attempting to use the printer. Repeatedly powering the printer on and off while the scanner is locked will not cause permanent damage in itself, but the underlying mechanical issue needs to be fixed before normal use can resume.

Q: Can I still use my Epson printer just for printing if the scanner lock is on?

No. Even on Epson all-in-one printers, the W-04 error caused by the scanner lock will prevent all functions — including plain document printing — until the error is cleared. This is because the printer's firmware performs a scanner initialization check at startup, and if the scanner carriage cannot move freely, the entire printer halts to avoid internal damage.

Abstract

The Epson error code W-04 means your printer's built-in scanner unit has its transport lock engaged, which is a physical locking mechanism designed to keep the scanner carriage secure during shipping or moving. When this lock is active, the printer cannot operate because the scanner head is physically prevented from moving. The fix is straightforward in most cases — you simply need to locate and release the scanner lock, which is usually a switch or tab found inside or on the underside of the printer.