I was told by Toyota service that the catalytic converter needs replacement.

What is your question?

The only reason I am aware of this is that a warning light appears on my dashboard. The car has 175,000 miles and the repair costs $2,100. I do not know if this is related but the windows always fog -up even on a cold dry day I need to turn the turn the front defroster on.

What makes this problem better or worse?

No relation

How long has your 2008 Toyota Prius had this problem?

A year