Epson ET-8550 DTF "Transport Error" and "Paper Jam" with No Obstruction - Causes and Fixes

Question

I have an Epson ET-8550 converted for DTF printing that has been running well for about 10 months. Recently, I started experiencing a back feed issue. I am getting a "Transport error" message even though the transport switch is not engaged, and also a "Paper jam error" when there is no paper stuck inside. I followed your videos but couldn't resolve the issue. I checked the PE sensor and it was completely clean, so I didn't replace it. The tube line cover is not getting caught either. When I power the printer off and back on, it allows me to run cleaning cycles and everything moves freely, but the errors return when I attempt to print.

Answer

Understanding the "Transport Error" and "Paper Jam Error" on the ET-8550

On the Epson ET-8550 (especially in DTF conversions), when you see:

• "Transport Error"

• "Paper Jam Error" (with no physical jam present)

-and the printer moves normally during cleaning cycles after reboot-this usually indicates a sensor feedback problem rather than a mechanical blockage.

Since:

• The transport switch is not engaged

• The PE (Paper End) sensor is clean

• The DTF tube cover is not snagging

• The printer can initialize and move freely during cleaning

The problem is likely occurring only when the printer enters print mode and relies on real-time carriage and paper width feedback.

Most Likely Cause: Worn or Failing CRPW Sensor Cable

One strong possibility is a failing CRPW sensor cable (Carriage Return / Page Width sensor cable).

Here is the part for reference:

8-Pin CRPW Sensor Cable for Epson ET-8500 / ET-8550
BCH Technologies Product Page:
https://bchtechnologies.com/products/8-pin-crpw-sensor-cable-page-width-cr-encoder-sensor-cable-for-epson-et-8500-et-8550-et8550-8550-dtf-dtg-printers
[https://bchtechnologies.com/products/8-pin-crpw-sensor-cable-page-width-cr-encoder-sensor-cable-for-epson-et-8500-et-8550-et8550-8550-dtf-dtg-printers?_pos=1&_sid=6a06b81d4&_ss=r]

Why This Cable Causes These Symptoms

The CRPW cable connects the carriage assembly to the page width and carriage position sensing system. Over time-especially in DTF conversions where:

• Ink mist and powder residue circulate inside the chassis

• The carriage moves more frequently and aggressively

• Heat and vibration increase

-the cable can:

• Develop micro fractures

• Lose signal integrity

• Create intermittent electrical contact

When this happens:

• The printer cannot properly detect carriage position.

• The page width sensor may report incorrect data.

• The printer falsely assumes a paper jam or transport fault.

That's why:

• Cleaning mode works (less sensor dependency)

• Printing fails (requires accurate CR position + paper tracking feedback)

This matches your symptom pattern very closely.

Why It's Probably NOT the PE Sensor

The PE (Paper End) sensor primarily detects whether paper is present. If it were failing:

• You would often get immediate paper feed errors.

• The printer might refuse to start feeding altogether.

• Cleaning cycles could also fail in some cases.

Since yours initializes properly and only throws errors during printing, the PE sensor being clean and functional makes sense.

Other Possible Causes to Rule Out

Before replacing the CRPW cable, verify the following:

1. Carriage Encoder Strip (CR Encoder Film)

• Check for ink mist, smudging, or fine DTF powder residue.

• Clean gently with lint-free cloth and isopropyl alcohol.

• Even slight haze can cause misreads.

2. Page Width Sensor Blockage

• Confirm no dried adhesive powder buildup.

• Check sensor alignment.

3. Mainboard Connection

• Reseat the CRPW cable on both ends.

• Look for oxidation on connector pins.

4. Carriage Movement Drag

Even if it "moves freely," ensure:

• No resistance at full left/right travel.

• No subtle drag from ink tubes.

• No warped DTF platen affecting alignment.

However, given your description and timeline (10 months of DTF use), cable fatigue is very realistic.

Why Rebooting Temporarily "Fixes" It

When you power cycle:

• The printer reinitializes.

• The carriage homes.

• Sensor readings are reset.

But once print data begins and the carriage moves at print speed, the weak cable signal fails under dynamic load.

This is classic intermittent flex-cable degradation.

Recommended Action Plan

1. Reseat and inspect the existing CRPW cable.

2. If symptoms persist, replace the CRPW cable.

3. While inside, inspect and clean the encoder strip.

4. Check tube routing one more time for subtle resistance.

If replacing the CRPW cable resolves the issue, that confirms the diagnosis.

Addressing printer issues can be quite complex due to the hands-on and mechanical nature of these machines. Unfortunately, we're not able to provide remote troubleshooting or step-by-step repair support. However, we do offer in-person evaluation and repair through our local diagnostic facility at BCH Technologies Printer Repair Service (https://bchtechnologies.com/printer-repair-service [https://bchtechnologies.com/printer-repair-service]). Because demand is high, we operate on a first-come, first-served basis, and it may take a few weeks before we can schedule a drop-off.

Our services are structured to repair either a complete printer or specific components, with clear procedural guidance. That said, we recognize our rates may not be the most budget-friendly. For that reason, we strongly encourage self-guided troubleshooting through online research. You can start with YouTube or visit our channel homepage at BCH Technologies YouTube Channel (https://youtube.com/@bchtechnologies [https://youtube.com/@bchtechnologies]). Use the search icon next to the "About" tab on the right side of the menu bar to look for specific topics. I receive dozens of questions daily about whether we have a video for certain problems. After nine years of creating content, it's difficult to recall every single one. Using YouTube's search function is the fastest way to locate relevant material, and it may even suggest helpful videos from other creators.

Thank you again for your continued trust and support. We truly appreciate you being part of the BCH Technologies community, and we hope this gives you a clear direction toward resolving your ET-8550 issue.