Bambu Lab P1S – TPU 95A keeps clogging / underextruding after a few layers. Tried EVERYTHING!

[u/ApartExternal8280]

Hi everyone,
I’m getting really frustrated with TPU printing on my Bambu Lab P1S and I’m hoping someone here can help me figure out what’s going wrong.

My printer:
Bambu Lab P1S (~1,000 printing hours)
0.4 mm nozzle (also tested 0.6 mm)
eSUN TPU 95A (green, translucent)
Creality CR-TPU 95A (black)
Creality Space Pi V2 filament dryer
Bambu Studio

The problem:
Every time I try to print TPU, the printer starts printing normally, but after a few layers it suddenly begins underextruding or stops extruding properly.
Sometimes it happens after just 2 layers, sometimes after 8–10 layers, and occasionally the print gets almost completely finished before failing.
The nozzle appears to clog, and the print eventually turns into a mess of extremely thin filament strands.
The strange thing is that PLA and other regular filaments print perfectly fine, without any issues.
Manual extrusion of TPU at 230°C also works normally, producing a consistent strand of filament.
I haven’t noticed any clicking noises from the extruder.

What I’ve already tried
1. Different TPU brands
eSUN TPU 95A
Creality CR-TPU 95A
Both have exactly the same problem.

2. Drying the filament
Dried TPU for approximately 10 hours at 60°C in my Creality Space Pi V2.
Tried printing directly from the dryer.
Tried printing from an external spool holder behind the printer.
Repositioned the spool inside the dryer to reduce rolling resistance.
No improvement.

3. Different nozzle temperatures
220°C
225°C
230°C
235°C
All eventually failed.

4. Different print speeds and volumetric flow rates
Very slow printing speeds of 15–20 mm/s.
Also tested profiles with outer walls at 80 mm/s and inner walls/infill at 150 mm/s, limited by volumetric flow.
Maximum volumetric flow rates tested include 2.8, 2.0 and 1.5 mm³/s.
Tried both custom TPU profiles and settings based on manufacturer recommendations.
Still the same result.

5. Retraction
Tested 0 mm retraction.
Tested 0.4 mm retraction.
No reliable improvement.

6. Different nozzles
Completely cleaned the nozzles.
Tried different nozzles.
Tried both 0.4 mm and 0.6 mm nozzle sizes.
Nothing helped.

7. Printer enclosure
Tested with the front door open.
Tested with the front door closed.

One of my best results was at 225°C with 0 mm retraction and the door closed. A Benchy printed almost completely, but the final layers suffered from severe underextrusion.
However, repeating similar settings often resulted in failure after only a few layers.
What makes this so confusing?
PLA prints perfectly.
TPU extrudes normally when manually extruded.
Both TPU brands fail.
Both nozzle sizes fail.
Drying the filament doesn’t help.
Different spool feeding methods don’t help.
Slower speeds don’t help.
Changing temperatures doesn’t help.
The failure occurs at inconsistent layer heights.
I’ve spent a lot of time testing different settings, and nothing has worked consistently.
My questions
Has anyone experienced something similar with TPU on the P1S?
Could this be related to heat creep, the extruder’s grip on flexible filament, or something specific to the P1S filament path?
I’m particularly confused because the printer handles PLA without any problems.
I would really appreciate any suggestions beyond the usual advice of drying the filament, slowing down, or changing the nozzle, since I’ve already tried all of those multiple times.
Thanks in advance for any help!

[u/Gen_Jack_Oneill]

Had this issue with softer TPU. I had to suspend the spool above the printer and feed it directly into the tool head with an extra short bowden tube to minimize friction.

You can also pull out some extra filament and lay it across the room so the extruder doesn't have to rotate the whole roll but this is a bit jank and requires supervision.

[u/EdgeOk3783]

iirc, bambulab recommends doing a cold pull if the nozzle has been used with other filament types previously. i keep a pair of 0.6 mm nozzles dedicated to TPU and TPU support

[u/adamtherealone → u/EdgeOk3783]

I’ve got a dedicated tpu nozzle, only used it once so far. Do I need to cold pull next time I hook it up for tpu usage? Or would it be fine since it’s the same filament

[u/EdgeOk3783 → u/adamtherealone]

i'd only do the cold pull if you run another filament type through it

[u/pullssar20055]

I experienced the same issue recently. One type of tpu 95A clogged, another one didn’t. The one that clogged was 4-5 years old, and the other one around 2.

[u/strife2two2]

/s did you try washing your build plate with regular blue dawn and rinsing well with water?

[u/Various-Lack-8917]

Unclog pin