2008 Prius 182K Miles, high temp coolant warning comes on intermittently over 50mph, if I put cabin heat on it blows cold air. Coolant reservoirs levels OK, radiator took a quart , topped off this AM. Problem still there but less since ambient temp is 50d . Water pump is turning
If you had to add a quart to radiator then there was a lot’s of air in it. Probably there’s still air in it. Bleeding the engine cooling loop on gen 2 Prius is not easy. You don’t have check engine light on? If it’s there can be a fault with coolant control valve that causes the heater not to get coolant sirculation.
