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error Braun
Error Code No lens filter
Lens filter not attached — necessary for accurate measurements.
? What Causes This
Lack or forgetting of lens filter.
✓ How to Fix It
Attach a new and clean lens filter before taking the temperature.
Source: page 13 of the official manual
From the manual
This error code appears in:
Braun Irt6520 Thermoscan Infrared Ear Thermometer