This is how a properly installed rain sensor should look:
If the sensor gel pad is missing, it will affect the sensitivity – or functioning – of the sensor. Many windscreens are being replaced, and the sensor pad is not renewed. The auto wiper function may still work, but it will not be as responsive, and sharp, as a sensor fitted with a gel pad.
Active Lane Assist, or Lane Departure Warning cameras are fitted differently and will not require a gel pad.