2012 Toyota Prius Owners Manual - Page 790

5-2. Steps to take in an emergency STEP 4 After the hybrid system has cooled down sufficiently, check the engine coolant level and inspect the cooling system for leaks. STEP 5 Add engine coolant if necessary. Water can be used in an emergency if engine coolant is unavailable. (→P. 494) Have the vehicle inspected at the nearest Toyota dealer as soon as possible. 5 When trouble arises 481