How to Fix Epson Scanner Error 100016 When the Scanner Moves Right but Will Not Return

Question:
I followed the troubleshooting steps for Epson scanner Error 100016, but the scanner still does not work correctly. The scanner carriage slowly moves to the right, then hangs and does not return. After that, Error 100016 appears again. What could be causing this, and what should I check next?

Answer:

Since your scanner slowly moves to the right but does not return, and then throws Error 100016 again, that behavior suggests the problem may be deeper than simple carriage obstruction or lubrication. In this case, one strong possibility is a scanner CIS unit malfunction.

The CIS unit stands for Contact Image Sensor. This is the part of the scanner assembly that reads the document as the scanner moves. In many Epson machines, if the scanner cannot properly initialize, detect home position, or complete its scan cycle, the printer may trigger Error 100016. When the scanner moves in one direction but fails to complete the return cycle, it often indicates one of the following:

1. A failing CIS unit

2. A defective scanner lamp / scanner light source

3. A carriage travel problem

4. A home position detection issue

5. A cable or connection problem between the scanner unit and the mainboard

Based on your symptoms, the scanner lamp is one of the first things I would check or replace. If the scanner lamp is weak, failing, or not illuminating correctly, the scanner may not initialize properly, which can lead to Error 100016. In some Epson units, the scanner starts moving, but because it cannot complete calibration or detect what it is supposed to see during startup, it stalls and then reports the error.

Here is how I would look at the issue in a practical sequence:

First, observe the scanner carefully when you power the machine on. Does the scanner light come on at all? Is it bright and steady, or dim and inconsistent? A weak or non-functioning lamp can absolutely cause startup scan errors. If the lamp is not behaving normally, then changing the scanner lamp is a reasonable next step.

Second, check whether the scanner carriage path is physically smooth. Even if the scanner moves to the right, resistance on the rail, contamination on the guide rod, or a dragging cable can prevent it from returning correctly. If the carriage binds mechanically, the machine may interpret that as a scanner fault and generate Error 100016.

Third, inspect the scanner belt, guide rod, and home position area. The scanner needs to know where its starting point is. If the home sensor area is dirty, blocked, or damaged, the scanner may move but fail to detect its return position. When that happens, it may keep trying, stall, or stop and throw Error 100016. Dust, grease buildup, broken plastic tabs, or a shifted sensor flag can all contribute.

Fourth, check the FFC cables or ribbon cables going to the scanner assembly. A partially loose or damaged cable can allow some movement while preventing proper signal communication from the CIS or lamp. That can create inconsistent behavior where the scanner appears alive but cannot complete initialization.

Fifth, if the scanner lamp replacement does not solve the issue, then the entire CIS assembly may be faulty. Since the CIS contains the imaging electronics and is critical to scanner calibration, a malfunction there can cause repeated Error 100016, especially when the motion sequence starts but never finishes correctly.

So, in short, my main recommendation based on your description is this:
It could be a scanner CIS unit malfunction. Try changing the scanner lamp first and see whether that resolves Error 100016. If it does not, then the next likely suspects would be the CIS assembly itself, the home-position detection system, or the scanner wiring.

One more point: the fact that the scanner moves slowly can also be meaningful. Slow scanner travel sometimes points to mechanical drag, insufficient drive force, or an electrical issue affecting the scanner motor circuit. So while the CIS and lamp are strong suspects, do not rule out a carriage rail issue or sensor-related failure.

Printer and scanner problems are often complicated because they involve physical parts, alignment, and real-time mechanical behavior. Because of that, we are not able to provide hands-on remote repair support or step-by-step live troubleshooting for printer repairs. We do offer an in-person diagnostic and repair service through our local repair facility (https://bchtechnologies.com/printer-repair-service). Due to demand, repairs are handled on a first-come, first-served basis, and it may take a few weeks before we are ready to receive your printer. We can work on either the full machine or specific components, and the service page explains how to proceed. That said, we understand our rates may not be the lowest option, so we strongly encourage self-help research as well. A good place to start is YouTube, including our BCH Technologies YouTube channel (https://youtube.com/@bchtechnologies). On the channel homepage, you can use the search icon next to "About" on the right side of the menu bar to look for topics related to your exact model or error code. We receive many questions every day about whether we have covered a specific issue in a video, and after creating videos for many years, the fastest way to locate one is usually YouTube's search function. It may also suggest useful videos from other channels that can help.

Thank you again for reaching out and for your continued support. We truly appreciate your engagement and the opportunity to help.