WARNING   WARNING:  Do not remove the coolant reservoir cap when the engine is on or the cooling system is hot. Wait 10 minutes for the cooling system to cool down. Cover the coolant reservoir cap with a thick cloth to prevent the possibility of scalding and slowly remove the cap. Failure to follow this instruction could result in personal injury.
WARNING   WARNING:  Do not allow the fluid to touch your skin or eyes. If this happens, rinse the affected areas immediately with plenty of water and contact your physician.
WARNING   WARNING:  Undiluted coolant is flammable and may ignite if spilled on a hot exhaust.

Your vehicle is equipped with two separate cooling systems. One is for cooling the engine and one is for cooling the inverter system controller that is specific to the hybrid operating system. The two systems operate similarly, with the inverter system controller cooling system generally operating at a lower temperature and pressure.
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Make sure that the coolant level is between the MIN and the MAX marks. If the coolant level is on or below the MIN mark, add coolant that meets the correct specification immediately.   See   Capacities and Specifications
Note:   Coolant expands when it is hot.The level may therefore extend beyond the MAX mark.
Adding Engine Coolant
  1. Remove the filler cap.
  1. Add engine coolant to the MAX mark, do not overfill.
  1. Replace the filler cap.Turn the cap clockwise until it contacts the hard stop.
Note:   Add a 50/50 mixture of antifreeze and deionized or distilled water, or prediluted engine coolant that meets the correct specification.See   Capacities and Specifications
Note:   In an emergency you can add just water to the cooling system to reach a vehicle service station.
Note:   Prolonged use of an incorrect dilution of engine coolant can cause engine damage, for example corrosion, overheating or freezing.
Adding Inverter System Controller Coolant
  1. Open the inverter system controller coolant reservoir cap.
  1. Use a funnel to add prediluted coolant to the inverter system controller coolant reservoir. Make sure that the level is between the MIN and MAX marks on the inverter system controller coolant reservoir. Use prediluted coolant meeting the Ford specification.   See   Capacities and Specifications
  1. Close the inverter system controller coolant reservoir cap.
Whenever you add coolant, check the coolant level in the inverter system controller coolant reservoir the next few times you drive the vehicle. If necessary, add enough prediluted coolant to bring the inverter system controller coolant level to the proper level.