Epson ET-8550 DTF Conversion Troubleshooting: How to Resolve Error Code 000031 and Ink Flow Issues

Question:
A customer asked why their Epson ET-8550-previously working well as a DTF-converted printer-suddenly stopped functioning after they installed a Highly Flavored CISS. After installation, only magenta ink printed, white ink did not flow, and after checking for air bubbles, clogs, and adjusting the capping station, the printer eventually displayed error 000031 and would no longer start up. The customer attempted various online fixes such as taping the APG lever, moving the printhead before the screech, cleaning the encoder strip, and adjusting the tubing, but nothing resolved the error. The machine is only two months old and no longer boots past startup.

Answer

Let's take a deep dive into what's happening with your ET-8550 and how error 000031 ties into the CISS installation and mechanical alignment issues.

Understanding the Ink Flow Issue (Magenta Printing Only, No White Ink)

Your initial symptom-only magenta printing while white ink failed to flow-strongly suggests one or more of these mechanical/flow-related problems:

1. Air in the White Ink Channel

White ink is heavier and more prone to settling or creating air pockets, especially after installing or repositioning the CISS. Even if the siphon test pulls ink through, a micro-bubble can still interrupt flow during printing.

Potential fixes:

• Re-prime the white ink lines thoroughly.

• Tap along the tubing to dislodge trapped micro-bubbles.

• Confirm the CISS tank elevation-is it too high or too low? ET-8550 is sensitive to head pressure.

2. Capping Station Seal Misalignment

When you mentioned adjusting the capping station, there's a chance the seal didn't re-sit correctly afterward. If the capping station loses vacuum, white ink-which thickens more easily-will be the first to drop out.

3. Tube Routing & CISS Obstruction

You noted that plastic parts were getting in the way. If tubing gets pinched, kinked, or restricted by the moving carriage, particular colors may drop out completely. White ink is especially vulnerable.

Error Code 000031 on the ET-8550

This is the major clue-and unfortunately, the most serious part. On the ET-8550, error 000031 almost always refers to a mechanical obstruction or sensor fault related to the APG lever or printhead carriage movement.

Important:
Error 000031 on the ET-8550 is NOT the same as the same error code on the ET-15000.
They share the number but not the meaning.

What Likely Happened

When installing the CISS, routing the tubes, or manually moving the printhead, the APG lever assembly in the rear of the carriage likely became misaligned. This lever controls paper gap adjustment and interacts with sensors that confirm proper printhead position.

If the APG lever is out of place or bent:

• The printer senses incorrect carriage height or resistance.

• It triggers 000031 at startup.

• The printer refuses to initialize until the internal mechanical alignment is corrected.

Why Your Fix Attempts Didn't Work

The procedures you tried-taping the lever, moving the printhead before the "screech," cleaning the encoder-are commonly suggested online, but for the ET-8550 specifically, they rarely solve an APG lever misalignment. That's because:

• The ET-8550's printhead carriage design is much harder to remove than other EcoTank models.

• The APG lever is buried in the rear of the carriage and not accessible without partial motherboard and frame disassembly.

• If the lever is popped out of its track, you cannot reseat it from the top or front.

The Real Fix

The APG lever assembly needs to be repositioned internally.
Unfortunately, this requires:

• Removing the entire top scanner unit

• Partially lifting the main carriage rail

• Re-engaging the APG lever into its correct slot from behind the carriage

I've been planning to shoot a step-by-step video because this issue has become extremely common with ET-8550 DTF conversions. Please follow my YouTube channel and you'll see this repair covered soon.

Important Notes for ET-8550 Owners Using CISS for DTF

• The ET-8550 is tight inside, and the CISS tubing must be routed absolutely precisely to avoid hitting the frame.

• Some aftermarket CISS units apply too much tension on the carriage, which can tug the APG lever out of its designed path.

• Always move the carriage slowly and by hand, and never force past resistance.

• Any resistance during startup (the "screech") is often the sound of the APG mechanism mis-syncing.

Repair & Support Options

Dealing with printer hardware-especially with conversions-often requires hands-on diagnostics. We can't offer remote repairs or one-on-one troubleshooting, but we do provide in-person evaluations through our diagnostic service at our local facility:
BCH Technologies Printer Repair Service [https://bchtechnologies.com/printer-repair-service]

Due to high demand, repair availability operates on a first-come, first-served basis, and wait times can be a few weeks. Our service covers full printer repairs or part-specific work, depending on what you need, and we provide clear instructions for drop-off. That said, our repair fees may not be the cheapest option, so we strongly encourage self-help when possible.

For independent troubleshooting, YouTube is one of the best resources. You can browse our channel by using the search icon next to the About tab on our YouTube homepage:
Visit our YouTube channel [https://youtube.com/@bchtechnologies]
With nine years of videos, I sometimes have trouble remembering which topics I've covered, but YouTube's search will show you my content and videos from other creators that may help as well.

Thank you again for reaching out and for your continued support. We appreciate your patience and your engagement with our content and products. If you continue to run into issues, keep an eye on our channel-I'll be posting guidance for this exact problem soon.