Epson Printer Keeps Ejecting Paper and Says "Load A4 Paper" - Troubleshooting Guide for PW Sensor Issues

Question:
My printer is still having the same issue even after I replaced the flex cable and encoder strip. I thought that would fix it, but it didn't. The rollers seem fine, and the sensor is not dislocated. There's no paper jam inside, and there is A4 paper loaded. The printer does pick up the paper, but once it starts printing, it immediately ejects it and shows a message like "Load A4 paper." What else should I check?

Answer:

Based on your description, the key symptom is this:

• The printer successfully picks up paper,

• But immediately ejects it,

• Then shows a "Load A4 paper" or paper-related error message.

This behavior strongly points to an issue with the Paper Width (PW) Sensor, rather than the parts you've already replaced.

What is the PW Sensor and Why It Matters

The PW (Paper Width) sensor detects the presence and width of the paper as it enters the print path. When working correctly, it tells the printer:

• "Yes, paper is loaded,"

• "This is the correct size (A4, etc.),"

• "Proceed with printing."

If the PW sensor fails or gives incorrect readings, the printer may:

• Think there is no paper loaded, even when there is,

• Or believe the paper size is incorrect,

• Trigger errors like "Load A4 paper" or similar prompts,

• Eject the paper immediately after pickup.

What You Should Check Next

1. Inspect the PW Sensor Mechanically

Even if the sensor looks "fine," check closely for:

• Dust, ink residue, or debris blocking the sensor

• A stuck or sluggish sensor flag/lever (small plastic arm that moves when paper passes)

• Misalignment or improper seating of the sensor assembly

Sometimes the sensor is not dislocated but still not moving freely, which causes false readings.

2. Clean the PW Sensor Area

Use:

• Compressed air

• A soft brush

• Isopropyl alcohol (if needed, applied carefully)

Ink mist buildup is very common, especially in Epson printers, and can interfere with optical sensors.

3. Check the PW Sensor Cable/Connection

Even though you replaced the flex cable, confirm:

• The PW sensor cable is firmly connected to the mainboard

• No bent pins or loose connectors

• No hidden damage along the cable path

A poor connection can mimic a failed sensor.

4. Test the PW Sensor Function

If you have access to service mode or diagnostic tools:

• Try checking sensor status readings

• See if the PW sensor changes state when you manually move the sensor flag

If it doesn't respond, the sensor is likely defective.

5. Replace the PW Sensor (if necessary)

If all else checks out, the PW sensor itself may be faulty. This is a common cause of your exact symptom:

• Paper feeds → immediately ejects → "Load A4" error

Replacing the PW sensor often resolves this issue completely.

Why Encoder Strip and Flex Cable Didn't Fix It

You replaced good candidates, but those parts mainly affect:

• Print head positioning (encoder strip)

• Signal transmission (flex cable)

They do not control paper detection, so the issue persists if the PW sensor is the root cause.

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems. Unfortunately, we're not able to provide remote troubleshooting, suggestions, or support for printer repairs. We do offer an in-person evaluation and repair service through our local diagnostic facility (https://bchtechnologies.com/printer-repair-service [https://bchtechnologies.com/printer-repair-service]). Due to high demand, we operate on a first-come, first-served basis, and it may take a few weeks before we can accept your printer. Our services are designed to repair either complete units or specific components, with clear guidance on the process. However, we understand that our pricing may not be the most budget-friendly, so we strongly encourage self-help through online resources.

You can begin by exploring YouTube or visiting our channel homepage (https://youtube.com/@bchtechnologies [https://youtube.com/@bchtechnologies]). Use the search icon next to the "About" section on the right-hand side to find videos on your specific issue. We receive many questions daily, and with hundreds of videos created over the years, searching directly is the fastest way to find relevant content. You may also discover helpful videos from other creators recommended by YouTube.

Thanks again for reaching out to us. We truly appreciate your patience and your continued support.