I have exact same problem. it was little cold in Chicago 5-7 F in some nights with wind chill below, So maybe i am thinking weather related. I have found many posting all over the web about this issue. I am thinking LEXUS should release RECALL about this issue because it cost 800-1000$ green bucks to replace + labor
if you have any advice holler me
at trance_boy2004@yahoo.com
thanks