Epson ET-4550 Scanner Error 4D: Causes, Safe Troubleshooting, and Repair Options

Question:

I have an Epson ET-4550 that has always worked normally for printing, copying, and occasional faxing. I recently tried to send a fax and accidentally pressed the Color button instead of the Black & White button. The printer said that sending a color fax would take some time, but then it could not pull in the document I was trying to fax.

After that, the printer displayed:

"Scanner Error 4D
Turn the power off and on again. If the error is not fixed, contact Epson Support."

I have turned the printer off and back on several times and even left it unplugged overnight. I also checked for paper jams and found a small piece of paper inside, which I removed, but the Scanner Error 4D is still showing. The printer does not respond when I press any buttons.

What does Scanner Error 4D mean on an Epson ET-4550, and is there anything else I can safely try?

Answer:

In your situation, the important error is Scanner Error 4D. Although the wording says "scanner," we would not assume from the message alone that the scanner glass or scanner software is the problem. Because this is an all-in-one printer with several internal motors, sensors, cables, and mechanical assemblies, an initialization failure can sometimes be reported through a scanner-related error even when the underlying problem involves another moving mechanism.

The fact that the printer is now stopping at startup and ignoring the control-panel buttons suggests that this is an internal hardware or initialization error, rather than simply a fax-setting problem. The accidental selection of a color fax probably did not damage the printer by itself. It is more likely that the error appeared at the same time the printer attempted to feed the document and initialize its mechanical systems.

Could the Small Piece of Paper Have Caused Scanner Error 4D?

Possibly.

Since you found a piece of paper inside the printer, an obstruction is one of the first things worth considering. A torn piece of paper can interfere with a sensor, roller, gear, carriage path, or another moving component.

However, because you removed the paper and Scanner Error 4D remains after multiple restarts, either:

• another small piece of paper or foreign object is still present,
• a sensor or mechanical assembly did not return to its expected position,
• a carriage or scanner mechanism is unable to initialize,
• a cable or sensor connection has developed a problem, or
• an internal electronic or mechanical fault has occurred.

The remaining error does not necessarily mean that the paper scrap was unrelated. A jam can sometimes put a mechanism out of position or expose an existing mechanical weakness.

Check the Automatic Document Feeder First

Because this happened while you were attempting to fax a document and the printer was unable to pull the page in, I would first inspect the ADF, or Automatic Document Feeder, at the top of the printer.

With the printer turned off and unplugged, remove any documents and open the accessible ADF covers. Look carefully for:

• torn paper,
• labels or adhesive material,
• staples or paper clips,
• scraps wrapped around rollers,
• debris near the paper sensors,
• rollers that appear displaced, and
• any object preventing the document path from closing normally.

Do not force the rollers or disassemble the mechanism unless you are comfortable doing so.

If the ADF cannot properly detect its home condition or a paper sensor remains activated, the printer may fail during initialization.

Check the Scanner Area for an Obstruction

The next area to inspect is the flatbed scanner.

Make sure there is nothing sitting underneath or interfering with the scanner lid. You can also look through the scanner glass and see whether the scanner carriage appears obviously stuck at an unusual position.

However, do not try to force the scanner carriage by hand. If the scanner mechanism is mechanically jammed, forcing it can damage the belt, gears, motor, or position-sensing components.

A scanner initialization problem could involve the scanner motor, belt, home-position sensor, carriage mechanism, wiring, or scanner electronics. Unfortunately, those components generally require disassembly to diagnose properly.

Do Not Manually Slide the Printhead Carriage

There is a user-reported workaround online suggesting that someone with a similar error should turn the printer off, open the printer, and move the printhead carriage back and forth manually.

We do not recommend doing that on the ET-4550.

Epson's own ET-4550 documentation specifically warns users not to move the printhead by hand because doing so may damage the product. Epson Support

Therefore, even though someone may have reported success after manually freeing a carriage, that procedure should not be treated as a verified repair for Scanner Error 4D.

With the printer turned off and unplugged, you can visually inspect the accessible carriage area for loose paper, foreign objects, or obviously displaced parts. You should not push or slide the printhead simply to see whether it moves.

Could This Actually Be a CR Carriage Problem?

It is possible, but we would not diagnose it as a carriage, or CR, problem based only on the 4D message.

This is what makes the error somewhat confusing. A printer goes through several initialization procedures during startup. If one assembly does not reach the expected position, communication between assemblies can stop and the printer may display an error that does not perfectly describe the failed component.

A carriage-related issue could theoretically involve:

• an obstruction in the CR path,
• contamination on the CR encoder strip,
• a carriage motor problem,
• a damaged timing belt,
• a home-position issue,
• a sensor problem, or
• an electronic failure.

However, since the printer specifically displays Scanner Error 4D, the scanner/ADF system should remain high on the list of possibilities unless inspection reveals an obvious carriage obstruction.

The Error Is Probably Not Being Caused by the Fax Setting

Pressing the Color button instead of the Black & White button would normally only change the way the fax is transmitted. It should not create a permanent hardware failure.

The timing may simply be coincidental. The printer was trying to feed the original, initialize the scanner, and prepare the fax at approximately the same time that something mechanical failed or became obstructed.

Therefore, there is no need to search for a setting that changes the fax back from color to black and white. The current Scanner Error 4D has to be resolved before normal fax, copy, scan, or printing functions can resume.

Try One Careful Power Reset

You have already done more than a normal restart by leaving the printer unplugged overnight, so repeatedly power-cycling it is unlikely to accomplish much more.

Nevertheless, after completing your visual inspection, you can perform one controlled restart:

1. Turn the ET-4550 off.
2. Disconnect the power cord.
3. Remove paper from the ADF and paper cassette.
4. Inspect the ADF, scanner area, and accessible paper path for remaining debris.
5. Make sure all covers and scanner units are fully closed.
6. Reconnect the printer directly to a wall outlet if possible.
7. Turn it on without attempting to fax, scan, or print.

Watch and listen closely during startup.

If you hear repeated clicking, grinding, buzzing, or a motor trying unsuccessfully to move something immediately before Scanner Error 4D appears, that information can help narrow the faulty mechanism.

If the printer immediately returns to the error without completing its startup sequence, the problem is increasingly likely to require mechanical or electrical diagnosis.

Software and Driver Reinstallation Are Unlikely to Fix This Particular Problem

Because Scanner Error 4D appears directly on the printer's own display and prevents the control panel from functioning, I would not make reinstalling Epson Scan, the printer driver, or the fax utility the first troubleshooting step.

Software troubleshooting is more appropriate when the printer itself initializes normally but the computer cannot communicate with the scanner. Epson distinguishes those types of computer-side scanning problems from faults occurring directly on the machine. Epson

Your symptoms point much more strongly toward a printer-side hardware or initialization problem.

What If Scanner Error 4D Still Does Not Clear?

Because you have already:

• restarted the printer multiple times,
• unplugged it for an extended period,
• found and removed a paper scrap, and
• confirmed that the control panel remains locked on the same error,

there may not be another simple external reset available.

At that point, proper diagnosis may require opening the ET-4550 and checking the scanner mechanism, ADF sensors, motors, wiring, flat-flex cables, carriage-related components, and possibly the main board.

We would avoid repeatedly powering the printer on if it is making abnormal mechanical noises. If a motor or gear is jammed, repeated startup attempts can sometimes make mechanical damage worse.

Addressing printer issues can be complicated because most failures require hands-on inspection and testing. For that reason, we're not able to provide individualized remote troubleshooting, repair instructions, or ongoing repair support. We do offer an in-person evaluation and repair service through our local diagnostic facility. You can learn more on our Printer Repair Service page [https://bchtechnologies.com/printer-repair-service].

Because demand for repairs is high, our service operates on a first-come, first-served basis, and there may be a wait of several weeks before a printer can be dropped off for evaluation. Our service options are designed for either complete printers or certain individual parts, with instructions provided on the repair-service page. We also understand that professional repair is not always the most economical option, particularly for an older printer.

For that reason, we strongly encourage self-help research when practical. You can start with YouTube or visit the homepage of our BCH Technologies YouTube channel [https://youtube.com/@bchtechnologies]. On our channel, use the search icon next to the About area to search terms such as ET-4550 scanner error, ET-4550 scanner repair, Epson ADF repair, or Epson scanner mechanism.

We receive dozens of questions asking whether we have a particular repair video. After creating videos for many years, it is difficult to remember every model and subject we have covered. Using YouTube's search function is usually the fastest approach, and YouTube may also recommend helpful videos from other repair channels.

Thank you again for contacting us and for taking the time to describe exactly what happened. The detail about the failed document feed, the Scanner Error 4D, and the paper scrap you found is useful information. We hope this gives you a safer direction for investigating the ET-4550 without risking additional damage to the printer.