BMW Repair: Faulty rain/light sensor, bmw roundel, rear view mirror

Question
I have a 3.0i petrol BMW X5, VIN LB 25026, build date November 03.

I have a problem with the rain/daylight sensor in the windscreen.

When the headlight switch is in the auto position and the ignition is first
switched on, the headlights come on for a few seconds, then go out for about
20-30 seconds before turning back on. During this period the wipers work
irregularly with the wiper switch in the automatic position, but once the lights
come on permanently, they will not work at all. The wipers also don't work in
the automatic position when the light switch is in the off position. They
operate normally in the full-time slow and fast positions.

The sensing element against the glass appears to have delaminated over
about 20% of it area. I have been advised by the people servicing this vehicle
that the rain/daylight sensor on the back of the windscreen is faulty and that
the only solution is to replace the entire windscreen.

This seems a bit drastic for what is probably a few cents worth of electronics.

Is there some simple workaround to this situation?

Thanks in anticipation of your help.

Answer
Barry, the rain/light sensor is under the rear view mirror cover and clips on to the windshield's optical element. It is very rare that the rain/light sensor goes bad. More common is what you are experiencing is the delaminating of the optical element in the windshield. In other words the sensor is good the windshield is bad. Replace the windshield. I install all windshields at my dealer and am very experienced with this particualr issue. Driver lower corner of the glass will have the BMW roundel on it if it is BMW glass. If it is BMW glass (which I recommend you use, I see this more often with aftermarket glass) and the vehicle has had the windshield replace less than two years ago then the part and labor is covered under the BMW parts warranty. X5 windshield jobs are usually around $750.00 USD.
-Evan