2012 Toyota Prius Owners Manual - Page 1347

5-2. Steps to take in an emergency STEP 4 After the hybrid system has cooled down, check the power control unit coolant level and inspect the cooling system for leaks. STEP 5 If necessary, add power control unit coolant up to the "F" line. Water can be used in an emergency measure if power control unit coolant is unavailable. (→P. 501) Have the vehicle checked at nearest Toyota dealer as soon as possible. 5