So...Ive got a used 2010 prius since July and had no problem at all! Then yesterday,my first problem came in on a cold morning...Ive saw that there is a technical bulletin for this problem at NEW!!! Service Bulletin for Engine Knocking at Startup T-SB 0012-10 | PriusChat but my car is 5 years old and not garanteed anymore (Im in Quebec by the way)...My question is...Is anyone here in Canada had the same problem and did your dealer repaired it? And the most important part...How much did you paid for that repair :-/ ? It's been 2 cold morning and 2 engine knocking in a row...I don't want to wait to not hurt the engine...Can it hurt the engine? I saw that it was caused by water accumlated in the intake...Will wait for your answers ... Thank!