Two problems related to coolant leaking have been reported for the 2012 Toyota Prius. The most recently reported issues are listed below.
2012 Toyota Prius ii, dealer maintained, now needs new engine due to blown head gasket. Mileage 151000. The car has run perfectly until a recent engine light came on. When it was brought into the dealership, the diagnosis was misfiring of 2 cylinders and coolant leaking into cylinders 3 and 4. There was no previous engine problems. An official complaint was filed with Toyota customer service. They responded that there was no fault on their end and I should have the engine replaced at an authorized Toyota dealer. A search for this trouble resulted in several other complaints of the failure of head gaskets in this year and model Prius.
Our 2012 Prius v has continuously been burning oil at an alarming rate. It was put through an oil consumption test at the dealership and they claimed not to know what the problem was (just that the car was getting older and we should probably buy a new one), even though they have issued a TSB to dealerships about this problem. At this point, we are barely able to drive the car any distance without having to put more oil in. We have always kept up on the maintenance for the vehicle, we recently replaced the head gasket and the coolant in the car, but now the car just runs hot with the fan running all the time and the oil is consistently burning. We've never had to put oil into the car ourselves between maintenance sessions and now they have us coming in to change oil every 5k miles instead of every 10k miles as before. Even then, we are still having to add oil in between visits. I bought the car as a commuter vehicle, it has about 200,000 miles on it, driving it 5 days per week, about 100 miles per day. Depending on the quote to fix it (from a non dealer because they won't acknowledge there's a problem), I will probably have to trade the car in at a minimal value in order to purchase a new car, which I really cannot afford to do right now. This problem is only occurring when the car is moving. There is no leak, as it would be evident on my driveway. I mostly drive the car on the highway.