Hi-I have a 2012 Prius V-bought it about two years ago-drive a lot have like 231 on it now. Last week heard this godawful sound… went to this private shop and he wasn’t around… went to Monro-which they always have a space opened to check out the car… well guy did scan with a little handheld scan… said cylinder one misfiring… had plugs with me and got them changed with one ignition coil… still had hesitation and weird sound… went back and guy said just drive it around for a couple of days-and come back if there is a problem… said was likely unburnt fuel… well ended up up going to Prius chats and saw Critic’s post on there that mentioned and described blown head gasket. Was able to take it next morning to shop that sold this Prius to the guy I bought car from and they just work on Priuses. They did head gasket and water pump with oil change for 2500… they checked egr said looked clean… there mechanic was going on vacation on Monday and figured can maybe get that cleaned thoroughly when they or another place may have more time…took it in Thursday at 11 am and got car back on Saturday at 1130am. didnt want to tell them to do it when they said looked “pretty good.” If I didn’t see Critic’s posting on Prius chat and saw a YouTube video which may or may not have been from critic as well -I likely would have driven it until head warped and would have needed a new engine… just wanted to say thank you to Critic for his contributions here and also on Prius Chat, which was helpful in describing and showing exact symptoms Prius has when head gasket is blown.