Hyundai Sonata 2017 Owner's Manual page 421

What to do in an emergency
WARNING
NEVER remove the
radiator cap or the
drain plug while the
engine and radiator
are hot. Hot coolant
and steam may blow out under
pressure, causing
injury.
Turn the engine off and wait
until the engine cools down.
Use extreme care when remov-
ing the radiator cap. Wrap a
thick towel around it, and turn it
counterclockwise slowly to the
first stop. Step back while the
pressure is released from the
cooling system. When you are
sure all the pressure has been
released, press down on the
cap, using a thick towel, and
continue turning counterclock-
wise to remove it.
6-8
6. If you cannot find the cause of the
overheating, wait until the engine
temperature has returned to nor-
mal. Then, if coolant has been
lost, carefully add coolant to the
reservoir to bring the fluid level in
the reservoir up to the halfway
mark.
7. Proceed with caution, keeping
serious
alert for further signs of overheat-
ing. If overheating happens again,
call an authorized HYUNDAI deal-
er for assistance.
Serious loss of coolant indi-
cates a leak in the cooling sys-
tem and should be checked as
soon as possible by an author-
ized HYUNDAI dealer.
CAUTION