Here is the description from the workshop manual.
Rain Sensor Reinitialization Setting
CAUTION: If the initialization is performed with water or dirt on the windshield, the rain sensor may not operate normally. Before performing the rain sensor initialization again, remove waret and dirt from the windshield.
NOTE:
When the ignition switch is turned to the ON position after replacing the rain sensor with a new one, the windshield condition is verified and the initial setting is stored
Perform the initial setting again in the following cases:
The windshield is replaced and the rain sensor is reused
The auto wiper system operates incorrectly (in my case in AUTO mode always performed a slow clycle when I turned the ignition switch to ON position, and didn't adjust the speed correctly to actual rain conditions.)
Remove water and dirt from the windshield surface
Turn the ignition switch OFF
Turn the windshield wiper switch to AUTO position
Within 10 s after turning the ignition switch to the ON position, turn the windshield wiper switch from AUTO to OFF position for five times and return it to the AUTO position.
CAUTION: If the operation is too fast, the windshield wiper switch position cannot be detected and the initial setting may not be performed. Operate the windshield wiper switch for one cycle (AUTO->OFF->AUTO) per 1 s.