I have had my car for +2 years now. Off and on - for no rhyme or reason that message pops up. Windshield - clean. I use the defog, wipers, etc. but many times it just stays. I have a suspicion its faulty. At the same time cant prove it as after a car wash the system behaves normally. Also sun glare has a major impact, many times it goes kaput when encountering flickering glare. I drive thru NY City and the tall buildings cause a lot of reflections off and on.
I have taken it to 2 dealerships : twice. Both time they came back: there's no TSB on this, there's nothing wrong. Personally, I feel mine's got a problem as even if there's no glare it just sometimes goes pop - error message. I have made sure the windshield is clean. Yes - the problem is more pronounced during winter, especially when abnormally cold/snow/etc.