Epson ET-8550 Print Head ID Mismatch: Does the QR-Code Number Have to Match the Printer's Head ID Sticker?

Question: My Epson ET-8550 has two different 32-character "print head ID" numbers-one on a sticker inside the printer (next to the serial number) and another next to a QR code sticker on the print head itself. Is the sequence next to the QR code really the print head ID, and if so, is it supposed to match the print head ID label inside the printer (assuming the head was never swapped)?

I'm trying to confirm this because my printer came back from a repair shop in worse condition. Now it shows an error at power-on (Google suggests it relates to print head temperature/overheating), it reports that something is stuck under the print head even though nothing is there, and there's a lot of ink spilled around the dampers. While inspecting it, I noticed the 32-character number on the print head doesn't match the 32-character head ID sticker inside the printer. I also noticed the warranty sticker peels off very easily and cleanly-have you seen that before?

Answer: 

Now, let's break down what you're seeing and what those IDs usually mean-then we'll connect that to the symptoms you described.

1) Is the 32-character sequence next to the QR code on the print head really the print head ID?

In many Epson models (including the ET-8550 family), the print head assembly often has:

• A QR code and

• A 32-character alphanumeric string printed near it.

That string is commonly a head identification / calibration-related code tied to that specific print head (or print head assembly batch). Epson uses identification data like this for manufacturing traceability and, in some designs, to help the printer apply head-specific drive/calibration values (how hard to fire nozzles, compensation tables, temperature behavior, etc.).

How to verify the QR-code content (quick check)

Your proposed method is solid: scan the QR code with your phone. Many times, the QR code will contain that same 32-character string or a related identifier. If your phone displays text that matches (or closely resembles) the nearby 32-character line, that's a strong indication you're looking at an internal ID for that head/assembly.

Important reality check: even when it is a "head ID," it's usually not something an end user needs to enter or "program" in normal repairs. In everyday troubleshooting, it matters only in special cases-typically when the printer or Epson service software is trying to validate or calibrate head-related parameters.

2) If it's a print head ID, is it supposed to match the 32-character "print head ID" sticker inside the printer?

Not always-and this is where people get understandably confused.

That interior sticker (next to the serial number) may show information such as:

• Printer serial number

• A head ID, head rank, head code, or calibration code recorded at the factory

Depending on Epson's manufacturing flow, that internal label can represent:

• The head ID that was installed at the factory at the time the printer was built, and/or

• A factory calibration reference that isn't guaranteed to match the exact visible head label you're looking at later (especially if the head assembly label format differs).

When a mismatch is a red flag

A mismatch becomes more suspicious if any of these are also true:

• The printer started throwing new errors immediately after service

• You see major ink mess around dampers/ink lines

• You get head temperature / overheat-related error code(s) on power-up

• The printer reports a carriage obstruction / "something stuck under the print head" even when it's clear

• The "repair shop" said Epson diagnostic software showed "lots of errors," but couldn't explain them clearly

In that scenario, a mismatch doesn't prove the print head was swapped-but it does support the possibility of:

• The head being swapped,

• The wrong head being installed,

• A head or carriage being reinstalled incorrectly,

• A connector/cable issue causing the printer to "think" the head temperature sensor is abnormal,

• Or an ink system disturbance (leak/air) causing cascading faults.

3) About the power-on error code: "print head temperature / overheating"

You mentioned you don't recall the exact code, but Google indicates it relates to overheating or print head temperature. When Epson throws a head-temperature-related error code, it often points to one of these categories:

Common causes

• Head FFC cables not seated correctly (or damaged): A slightly misaligned flex cable can cause sensor readings to fail, or the printer to interpret a sensor as out of range.

• Connector contamination (ink, cleaning fluid, moisture, corrosion): If ink leaked or was spilled near the carriage board or head connectors, it can create shorts or false readings.

• Carriage board damage: If ink gets onto the carriage PCB, it can cause all kinds of strange errors.

• Wrong head / incompatible head revision: Less common, but possible if a head from a different unit or revision was installed.

• Actual overheating: Typically less likely at power-on unless there's a sensor or electronics fault-true overheating usually requires firing activity.

Why this matters with your "ink spilled around dampers" detail

Ink around the dampers and head area is a major clue because it increases the risk of ink reaching:

• The head ribbon cables

• The carriage PCB

• The connectors

• Or pooling where it shouldn't be

Even a small amount of ink in the wrong place can create electrical problems that look like temperature sensor or head-driver faults.

4) "Something is stuck under the print head" but nothing is there

This message often corresponds to the printer detecting abnormal carriage movement or resistance. If nothing is physically stuck, likely causes include:

• Carriage path obstruction that isn't obvious (a slightly displaced plastic guide, foam pad, or cable routing issue)

• Encoder strip contamination or misalignment (the clear strip the sensor reads for carriage positioning). Ink mist or smears can confuse position feedback.

• Encoder sensor issues

• Carriage not seated properly after reassembly

• Ribbon cables routed incorrectly, dragging or snagging

• Wiper/capping station misalignment causing the head to bump into service station parts

Given your timeline (worked before service, unusable after), this kind of error strongly suggests something changed mechanically or electrically during the repair attempt.

5) Heavy ink around dampers: what it usually indicates

Dampers are meant to regulate ink flow and prevent backflow/air ingestion. A big ink mess around them can be caused by:

• Damper not seated or O-rings not sealing

• Ink line not fully locked

• Cracked damper, cracked manifold nipple, or damaged ink line

• Excessive priming / improper suction method

• Cap station issues causing ink to pool and migrate where it shouldn't

Once air enters the system-or a seal is compromised-clogs and starvation can get worse, and error codes can snowball.

6) Warranty sticker peeling "very easily and cleanly"

Yes, that can happen. Some warranty labels use adhesives that:

• release cleanly if the surface is slightly oily/dusty,

• are affected by heat, humidity, or age,

• or lift easily if cleaning solutions were used nearby.

It's not definitive proof of tampering by itself. However, in the context of "it came back worse + lots of new errors," it's another detail worth documenting with photos.

What your original "head ID" point gets exactly right

Your proposed answer is directionally correct:

• In most real-world repairs, head ID data is not something the average user needs to worry about.

• Epson's encoded head information is typically used for calibration/compensation, not for routine maintenance.

• So yes-99% of the time, it's not the lever that fixes the printer.

That said, in your situation, the head ID mismatch isn't important because it needs to be "typed into the printer"-it's important because it may be a clue that the head or carriage system was swapped, disturbed, misassembled, or contaminated during service.

Addressing printer issues can get complicated because the problems are hands-on and often depend on what's physically happening inside the machine. Because of that, we're not able to provide remote troubleshooting, step-by-step repair instructions, or remote support for printer repairs. We do offer an in-person evaluation and repair service through our local diagnostic facility, BCH Technologies Printer Repair Service (https://bchtechnologies.com/printer-repair-service). Due to high demand, we operate first-come, first-served, and it can take a few weeks before we're able to accept a drop-off. Our service options are structured to repair either the whole printer or specific parts with clear intake steps. That said, we also recognize our rates aren't the cheapest-so we strongly encourage self-help through careful online research. A great starting point is YouTube, especially our channel homepage, BCH Technologies on YouTube (https://youtube.com/@bchtechnologies). Use the search icon near the "About" area on the right side of the menu bar to find videos by topic. I receive many questions every day asking if we have a video for a specific issue, and after nearly a decade of uploads it's tough to remember every single one-YouTube search is the fastest method. Plus, YouTube may recommend other relevant videos from other creators that can also help.

Thanks again for contacting us, and thank you for supporting what we do. I'm sorry you're dealing with this-especially after you did the right thing by taking it to a certified shop. I truly hope you're able to get the ET-8550 back to a stable, usable state as soon as possible.