Misfire rattling sound on a warm car Prius Gen2

Maybe your code reader is not capable enough to read the Prius can bus system this is more than likely to see if this is the case unplug one of your coils creating a misfire and scan the car does your scanner tell you that the cylinder you unplugged is misfiring? That's a very basic code to have to analyze so there are things like that at play sometimes too The generation 2 is not really known for rattling and carrying on like the 2010 through 2016 or 15 but any car can have a blown head gasket and have the fire being quenched by the leakage through the head gasket of water etc It's just quite rare in this model especially at 100,000 mi my goodness so hopefully we'll be able to get through it and it's something less costly to deal with mean you can always take the water out of the equation for a couple minutes and drop the level low enough to where it's not enough in the block to be getting pumped in to the cylinders for test purposes won't hurt a thing especially if it turns out to be the case anyway.