Last winter I got the CEL on the coldest day of the year (2 or 3 times). It only happens when I park the car for up to 8 hours and temp is below 19F (-7C).

What I noticed was after 2-3 engine restarts the light goes off, or if I leave the car overnight CEL is gone the next day (covered garage). No CEL in the summer or any symptoms, car drives excellent.

Yesterday we got a cold snap and car is left at the train station for 9 hours, get back and CEL pops up, so I got my INPA and read the codes, 29F4 and 29F5.

What could be causing this on cold days alone? its a 2007 3.0....