Cold start knock or rattle
Cold start knock or rattle can also be due to a bad or sticking EGR valve which sticks open at startup. 2010-2012 Prius has a EGR software update by Toyota for the rattle
Cold start knock or rattle can also be due to a bad or sticking EGR valve which sticks open at startup. 2010-2012 Prius has a EGR software update by Toyota for the rattle