121
Moderate
Formlabs · Professional Resin 3D Printers
Resin Tank Not Detected - Tank Sensor Not Triggered
Quick Answer
Error code 121 on your Formlabs Professional Resin 3D Printers means: Resin Tank Not Detected - Tank Sensor Not Triggered. This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
How to Fix It
1
Remove the resin tank and reinsert it, ensuring it clicks firmly into the mounting position
2
Clean the tank base and identification contacts with isopropyl alcohol and a lint-free cloth
3
Inspect the tank mount area in the printer for any cured resin debris and clean if necessary
4
Verify the tank is the correct version for your printer model (v1 vs v2 vs v2.1 for Form 3 series)
5
Try a different tank if available to determine if the issue is the tank or the printer sensor
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Replacement resin tank (model-specific with correct version number)
Isopropyl alcohol for cleaning contacts
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