P2S – “Failed to Extrude Filament” / High Feed Resistance

Bambu Lab P Series Bambu Lab P2S
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P2S – “Failed to Extrude Filament” / High Feed Resistance – Extensive Troubleshooting Done

Hi everyone,

I’m running into an issue with my P2S where I’m consistently getting:

  • “Failed to extrude filament”

  • AMS feed resistance too high (slot 1 initially, now across multiple slots)

I’ve done a pretty thorough round of troubleshooting and wanted to document everything before replacing parts.

:wrench: Symptoms

  • Filament reaches the extruder/hotend but does not extrude

  • Very high resistance when attempting to manually push filament

  • Cold pull does pass through, but normal extrusion fails

  • Same issue occurs across multiple AMS slots (not isolated to one slot)

:test_tube: Troubleshooting Performed

AMS / Filament Path

  • Tested multiple AMS slots → same issue

  • Verified filament reaches extruder

  • Trimmed filament tips clean (angled cuts)

  • Checked and cleared PTFE tubes (no obstructions)

  • Reduced tube curvature / checked routing

Extruder Assembly

  • Fully disassembled extruder → no broken filament or debris

  • Gears appear clean and functioning

  • Able to feed filament up to hotend

Nozzle / Hotend Behavior

  • Removed nozzle → visually clear (light passes through)

  • Installed nozzle again → no change

  • Attempted manual extrusion at 260–270°C

    • Filament is very hard to push or won’t move

  • Performed multiple cold pulls using cleaning filament

    • Filament passes through during cold pull

    • Still cannot extrude normally afterward

Additional Observations

  • Filament does not melt properly when manually inserted (top remains solid)

  • Extrusion only occurs during cold pull cycles, not during normal operation

  • Printer throws consistent extrusion failure warnings

:brain: Current Theory

At this point, I suspect a:

:backhand_index_pointing_right: Partial clog or restriction inside the heatbreak (hotend assembly)

Reasoning:

  • Not AMS-related (multiple slots tested)

  • Not extruder-related (clean and functional)

  • Not nozzle (verified clear)

  • Cold pull works, but pressure-based extrusion fails → suggests internal restriction

:red_question_mark: Question

Does this sound like a confirmed heatbreak clog / hotend failure, or is there anything else I should check before swapping the hotend?

Appreciate any insight — I’ve tried to be as thorough as possible before replacing parts.

Thanks!

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Hi user_2524434464, thank you for the detailed information, it really does help. I think you’ve gone through most troubleshooting steps, the only real way to confirm it’s a hotend failure is to replace and test. It’s a step I probably would have performed sooner on your troubleshooting journey, since it’s super easy and cheap to do, especially if you have spares available (in any size). I wouldn’t hesitate to replace as soon as possible, and when you do, please report back.

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What do you mean by "Reduced tube curvature / checked routing"?
Have you altered the PTFE-tube that goes into the print head in any way? A curvature that is too abrupt can/will cause high(er) resistance. And so can re-routing of the tube. Like with the (extra) clamps that some people advise.

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Reducing the curvature would increase drag on the filament and over-work the motors, I assumed and I hope he mistyped; if anything, the PTFE tube going into the hotend should have as wide of an angle as physically allowable.

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Thanks for the clarification — I did not modify or tighten the PTFE tube routing.

To clarify, I did not reduce the bend radius or add any clamps. The PTFE path remains in its original configuration with a smooth, natural curve into the print head.

The issue was ultimately resolved through cleaning and flow restoration. I performed multiple cold pulls and purges using cleaning filament, which removed what appears to have been a partial internal restriction in the hotend.

After that, I tested printing both with an external spool and with the AMS. The printer is now feeding and extruding normally, with no clicking or resistance errors observed.

At this point, everything appears to be functioning as expected.

3 Likes
6

Thanks for the clarification — I did not modify or tighten the PTFE tube routing.

Thank you for responding.

The issue was ultimately resolved through cleaning and flow restoration. I performed multiple cold pulls and purges using cleaning filament, which removed what appears to have been a partial internal restriction in the hotend.

After that, I tested printing both with an external spool and with the AMS. The printer is now feeding and extruding normally, with no clicking or resistance errors observed.

At this point, everything appears to be functioning as expected. Currently doing a third print with AMS PRO 2. I have added a switching adapter to provide a dedicated power source.

3 Likes