Structural / Functional Issue

How to Fix Under-Extrusion (Sparse Lines / Missing Material)

Step-by-step fix for under-extrusion (sparse lines / missing material) on Bambu Lab printers including X1C, H2D, P1S, and A1.

Related Bambu Studio Error Codes

1200-801612008016

How do I fix under-extrusion (sparse lines / missing material)?

1
Check for a partial nozzle clog — do a cold pull (set nozzle to 90°C for PLA, pull filament out to remove debris). After printing fiber-filled filaments (PA-CF, PETG-CF), residue narrows the nozzle channel over time.
Setting: Nozzle maintenance
2
Increase nozzle temperature by 5–10°C or reduce print speed. Under-extrusion often means the filament can't melt fast enough at current speed.
Setting: others.nozzle.nozzleTemp
3
Run flow rate calibration in Bambu Studio (Calibration > Flow Rate). If the flow ratio is too low, every line will be under-extruded.
Setting: Flow ratio

Pro tip: Under-extrusion weakens parts significantly. Select "High Strength" above to see wall and infill settings that compensate for any remaining flow inconsistency.

Related Print Issues

Weak Layer Adhesion / Delamination Part Breaking Along Layer Lines Poor Dimensional Accuracy Part Too Flexible / Not Stiff Enough Bed Adhesion Failure / Part Detaching

Still having issues?

Try our AI-powered troubleshooter — describe your problem in your own words and get personalized fixes.

Open AI Troubleshooter

Browse All Print Issues

Uneven First Layer Stringing / Oozing Visible Layer Lines Elephant Foot (First Layer Bulge)Warping / Curling / Lifting Visible Z-Seam Rough / Droopy Overhangs Blobs / Zits on Surface Ghosting / Ringing Weak Layer Adhesion / Delamination Part Breaking Along Layer Lines Poor Dimensional Accuracy Part Too Flexible / Not Stiff Enough Bed Adhesion Failure / Part Detaching Support Removal Damage / Scars Infill Showing Through Walls Heat Creep / Clogging Mid-Print Thin Walls Breaking / Gaps in Thin Features Part Deforms in Heat / Sun Spaghetti / Print Detached Mid-Print Over-Extrusion (Blobby / Too Much Material)Nozzle Clog (Blocked / No Extrusion)Extruder Clog (Filament Stuck in Gears)Filament Sticking to Nozzle (PETG)Bad Bridging Quality (Sag or Snap)Belt Pattern / VFA (Vertical Fine Artifacts)Gaps / Holes in Top Layer Different Gloss / Sheen on Different Areas Interlayer Cracking (ABS/ASA/PC/PA)Model Collapsing / Nozzle Hitting Print Wet / Damp Filament (Popping, Bubbles)Layer Shifting (Layers Offset Mid-Print)AMS Filament Tangled / Spool Stuck AMS Filament Ran Out Mid-Print AMS Cutter Stuck / Failed to Cut Filament Pile-Up in Waste Chute Build Plate Not Detected / Marker Missing Power Loss / Print Resume After Outage Hotend Fan Speed Abnormal / Stopped Homing Failed (X/Y/Z Axis)AMS Filament Change Failed / Purge Timeout Chamber Temperature Too High (PLA/PETG Softening)Print Paused — Door / Cover Open Printing CF Material with Wrong Nozzle CR Touch / BLTouch Leveling Failure Sprite Extruder Clicking / Grinding Filament X/Y Belt Tension Issues (Loose or Over-tight)Klipper Input Shaper / Pressure Advance Tuning Thermal Runaway Protection Triggered Bed Leveling Springs Losing Tension Creality Print / Slicer Compatibility Issues PTFE / Bowden Tube Wear or Gap IDEX Dual Extruder Calibration Offset Luban Connection / WiFi Transfer Issues Module Switching Problems (3D Print / CNC / Laser)Heated Bed Temperature Uniformity (Large Bed)