Push the lever into the desired position ⇒ fig. 94: 
(A) Rain sensor off (windshield wiper lever home position). 
(B) Rain sensor active – automatic wiping as needed. 
(1) Adjusting the sensitivity of the rain sensor: 
–  Move switch to the right – high sensitivity. 
–  Move switch to the left – low sensitivity. 
After switching the ignition off and back on again, the rain sensor 
stays on and works again with the wiper lever in position (B). 
Possible reasons for changes in the way the rain sensor works 
The rain sensor may misread what is happening in the detection zone 
of its sensitive rain-sensor surface ⇒ fig. 95 (arrow) and not work for a 
number of reasons, which include: 
  Worn out wiper blades: Worn out wiper blades may leave a film of 
water or wiping streaks; this can cause the wipers to run longer, to 
wipe more often, or to wipe continuously at high speed. 
  Insects: Insects hitting the sensor may trigger the wipers. 
  Salt streaks: Salt streaks on the windshield from winter driving can 
cause wiping more often or continuously on glass that is almost dry. 
  Dirt: Caked-on dust, wax, any other buildup on the windshield (lo-
tus effect), or car-wash detergent residue can lower the rain sensor's 
sensitivity and cause it to react too slowly or not at all. 
  Crack or chip in the windshield: If a stone hits and chips the wind-
shield while the rain sensor is on, this will trigger a wiper cycle. After 
that, the rain sensor will recognize the change and recalibrate itself to 
respond to the sensitive surface's reduced detection zone. Depending 
on the size of the chip, the sensor's reaction pattern may or may not 
change. 
  WARNING 
The rain sensor cannot always recognize rain and activate the 
wipers. 
  Switch the wipers on manually when water on the windshield 
reduces visibility. 
  Clean the rain sensor's sensitive surface ⇒ fig. 95 (arrow) regular-
ly and check the wiper blades for wear or damage.