Knowing what causes misting is half the solution to this problem. Short of stating the obvious, moisture is present! More correctly the air is humid and marginally warmer than the outside air temperature - which when hitting the lens causes condensation. Test this by running a very cold water onto the outside of the lens and see if any misting starts to show. Provided the rear cover is securely clsed/sealed and there are no broken seals or cracks, then the air inside which is humid got in there somehow. now ask yourself has the dealer or you changed a buld some time ago - this may have been weeks ago. What was the air temperature and humidity like when this was done? Chances are it was humid. The air must be bone dry. Solution is to remove unit and back plate, place in airing cupboard - opeining upwards for 30 minutes and reseal back inside cupboard and you have a nice clear unit.
2003 FSi SE in Ebony Black Pearlescent; DIS; Winter Pack; Sports Steering Wheel; Copilot Light and Upgraded bulbs
2003 FSi SE in Ebony Black Pearlescent; DIS; Winter Pack; Sports Steering Wheel; Copilot Light and Upgraded bulbs