Hi I have recently had a st170 with all the upgraded lights and leather seats and auto climate control now while cleaning it I have noticed a small round purple peace of plastic fitted in the top of the drivers side of the dash board does anybody know what this is for please help cant find anything on the internet of what this could be

 

Put up a pic mate, a picture says a thousand words

 

The purple circle is a sun load sensor. it measures the intensity of the sunlight and is fitted on the focus with climate control.

 

Theres your answer.