Summary
My K2 Pro aborted a 2-hour PETG print at 93% due to heat creep. I traced the root cause to two settings in Creality’s own CR-PETG @Creality K2 Pro 0.4 nozzle profile, and I can document it with the printer’s own telemetry.
The printer is now down, and not because of the jam: it is down because I cannot safely follow the repair documentation. The QR code that Creality printed on my extruder points to a page for the K2 Plus. The K2 Pro wiki pages serve every single image from the K2 Plus and K2 folders. And the hardware in those images is not the hardware on my machine.
I am not asking for a refund or an RMA. I am asking for documentation that matches the machine I own.
1. The machine
| Model | Creality K2 Pro (300 × 300 × 300) |
| Firmware | {{FIRMWARE}} |
| Filament | CR-PETG, slot A of the CFS, 18% RH measured by the CFS itself |
| Slicer | Creality Print 7.2.1.5476 |
| Profile | CR-PETG @Creality K2 Pro 0.4 nozzle (stock, unmodified) |
| Nozzle / bed | {{NOZZLE_TEMP}} / {{BED_TEMP}} |
The job was a flat calibration plate: 18 slots plus 8 small T-nuts. Declared time 1 h 55 min. It aborted at 93%, at 107.6 min of 115. The on-screen message was the printer seems to be printing without extrusion, and the retracted filament came out stuck.
2. Root cause: heat creep, caused by the stock profile
Two settings in the CR-PETG profile, compared against Creality’s own Generic PETG:
| Setting | CR-PETG @K2 Pro |
Generic PETG |
|---|---|---|
during_print_exhaust_fan_speed |
0 | 60 |
activate_chamber_temp_control |
1 | 0 |
chamber_temperature |
35 | — |
With the exhaust fan off and chamber control on, after two hours the chamber read 35.8 °C with the heater already off — that is pure accumulated heat. The air that cools the extruder heatsink is entering already warm, so the filament softens above the melt zone and grips the heatbreak.
My part was the worst possible case for this: 18 slots and 8 tiny T-nuts means continuous retraction for two hours, and every retraction pulls softened material up into the cold zone.
3. The evidence, from the printer’s own telemetry
The CFS measuring_wheel records actual filament advance. Its derivative shows the jam developing before any error fires:
11:12:43 → 108
11:13:19 → 49
11:13:55 → 25
11:14:32 → 0 ← full stall
11:15:07 → machine pauses (detection worked correctly)
The error codes only arrived four minutes later, during the recovery attempt:
-
key784—软件触发持续过流(sustained overcurrent), value"e"= extruder -
key865—retrude error, failed to exit connections, slot[1,"A"]
Two observations I would like to pass on rather than complain about:
-
The stall detection did its job. The machine paused on its own. Credit where it is due.
-
The error codes describe the symptom, not the cause. Anyone reading only
key784will chase an extruder motor fault. The measuring wheel gives the cause and the exact minute. If that signal were surfaced in the UI, or the codes were documented publicly, this would be a five-minute diagnosis instead of an afternoon.
I also confirmed it was not moisture: the CFS read 18% RH, and the tip of the retracted filament was drawn out into a thread — the heat creep signature — not bubbled or swollen.
The fix I applied to my own profile: during_print_exhaust_fan_speed to 60, matching the generic profile. I would ask that Creality review this value in the shipped CR-PETG profile. It is presumably tuned to prevent warping, which is reasonable for a tall part — but on a two-hour flat print with continuous retraction it produces the failure above.
4. Where I am actually blocked: the documentation
After a sustained overcurrent event the extruder gears have to be cleaned — the motor forced against a stuck filament and leaves shavings between the teeth. That means removing the extrusion assembly. This is where it stops.
4.1 The QR code on my extruder points to the K2 Plus
Creality printed a label directly on my extruder: How to Remove the Extrusion Assembly — Scan the QR code to view the detailed tutorial.
I decoded that QR from a photograph of my own machine. It resolves to:
https://wiki.creality.com/en/k2-flagship-series/k2-plus/jammed-filament
k2-plus. My machine is a K2 Pro.
And the K2 Pro page is not missing — it exists and returns HTTP 200:
https://wiki.creality.com/en/k2-flagship-series/k2-pro/jammed-filament
So the physical label, printed by Creality on a K2 Pro, sends the owner of that K2 Pro to another model’s page while the correct page sits there unused.
4.2 The K2 Pro pages are other models’ pages relabelled
| Page | URL says | Images are served from |
|---|---|---|
k2-pro/jammed-filament |
k2-pro | /products/fully-enclosed/**k2plus**/ — 23 of 23 |
k2-pro/replace-ptfe-tube |
k2-pro | /products/fully-enclosed/**k2**/ — 23 of 23 |
k2-pro/jammed-filament is subtitled Applicable for K2 Plus/K2 Pro/K2, and every internal link goes to a /k2-plus/ page (Replace K2 Plus Extruder Front Cover, General Troubleshooting Steps for K2 Plus Filament Loading and Unloading).
It also never mentions the PTFE tube — which is precisely the step I am stuck on.
I understand shared documentation across a product family. It works only while the hardware is shared. Here it is not.
4.3 The hardware in the documentation is not the hardware on my machine
| Wiki / official video | My machine | |
|---|---|---|
| Extrusion assembly | Grey, CREALITY logo | Black |
| Label on the assembly | none | printed instructions + QR |
| Tube connector | small part, released by hand | moulded black collar |
| Tools needed | none | I could not release it by hand |
The official video for my own model — Service Tutorial K2 Pro Extrusion Jam Handling (7FbNPXv7cWw) — shows a lever-type connector that my machine does not have.
There is a further inconsistency worth pointing out. The label on my extruder gives a two-step procedure — use an Allen wrench to remove the three screws shown, then press the tension block to separate the gear, then pull the housing outward — and never mentions the filament tube at all. The video and the wiki both begin by disconnecting that tube. So the label on the assembly and the tutorial it links to do not even describe the same procedure, and an owner has no way to tell which one applies to the hardware in front of him.
So the label Creality printed on the new revision of the assembly points to documentation for the old revision of a different model. I have attached a photo and a short video of my actual hardware.
I stopped there. I am not going to force that connector with pliers on guesswork: the K2 Plus wiki has an entire page about this connector failing to hold the tube, and the connector is sold as a spare part — it is a part that breaks. If I break it, the printer is down until a replacement arrives.
That is the real cost here. The jam was a two-hour print. The documentation is what turned it into a printer that has been sitting unusable.
5. For other K2 Pro owners
If your extrusion assembly is black with a printed label and a QR code, do not assume the wiki images match your machine. Check before applying force to the tube connector. And if you print long PETG jobs with heavy retraction, open the CR-PETG profile and look at during_print_exhaust_fan_speed before you start.
6. What I am asking for
-
Repoint the QR on the K2 Pro extruder label to the K2 Pro page that already exists.
-
Publish K2 Pro documentation with K2 Pro photographs, covering the current extrusion assembly revision and, specifically, how to release the filament tube connector on that revision. One page with correct images resolves this.
-
Review
during_print_exhaust_fan_speed = 0in the shippedCR-PETG @Creality K2 Proprofile for long, retraction-heavy jobs. -
Consider documenting the
keyNNNerror codes, or surfacing the measuring-wheel signal. The data is already there — it just is not reachable by the person who needs it.
I have been running this machine for weeks and reporting what I measure, including the case where I was the one who got it wrong. I am not looking for a confrontation. I would just like the documentation to describe the machine that is in my workshop.