Techno Line WL 1020 Manuel D'utilisation page 33

Restore factory calibration parameters:

Press and hold the "-" button if you want to restore factory
calibration parameters.

When the LCD displays "RES", press the "SET" button to
confirm and then the factory calibration parameters are
restored.
Troubleshooting:

Do not touch the sensor or don't store the item in
packaging materials with strong smell, so as not to affect
the accuracy of the sensor.

WL 1020 should not be placed in a polluted environment
for a long time (eg: sealed boxes, contaminated
environments).

Before the WL 1020 is used, it should be placed in a well-
ventilated environment to work for more than 1 hours to
EN13