2021 HYUNDAI SONATA HYBRID coolant

While Driving
6-34
CUSTOM mode
In CUSTOM mode, the driver can select separate modes
and combine them on the
infotainment system screen.
-Engine/Transmission: ECO/SPORT
-Steering wheel: SPORT
For more details, refer to the separately
supplied manual with your vehicle.
• When CUSTOM mode is selected
by using the DRIVE MODE button,
the CUSTOM mode indicator will
illuminate.
ECO mode
When the Drive Mode is set
to ECO mode, the engine and
transmission control logic are
changed to maximize fuel
efficiency.
• When the ECO mode is selected by
using the DRIVE MODE button, the
ECO indicator will illuminate.
• Whenever the engine is restarted, the
drive mode remains in ECO mode.
Information
Fuel efficiency depends on the driver’s
driving habit and road condition.
When ECO mode is activated:
• The acceleration response may be
slightly reduced as the accelerator
pedal is depressed moderately.
• The air conditioner performance may
be limited.
• The shift pattern of the automatic
transmission may change.
• The engine noise may get louder.
The above situations are normal
conditions when ECO mode is activated
to improve fuel efficiency.
Limitation of ECO mode operation:
If the following conditions occur while
ECO mode is operating, the system
operation is limited even though there is
no change in ECO indicator.
• When the coolant temperature is low:
The system will be limited until engine
performance becomes normal.
• When driving up a hill:
The system will be limited to gain
power when driving uphill because
engine torque is restricted.
• When the accelerator pedal is deeply
depressed for a few seconds:
The system will be limited, judging
that the driver wants to speed up.

While Driving
6-134
Driving in Flooded Areas
Avoid driving through flooded areas
unless you are sure the water is no
higher than the bottom of the wheel hub.
Drive through any water slowly. Allow
adequate stopping distance because
brake performance may be reduced.
After driving through water, dry the
brakes by gently applying them several
times while the vehicle is moving slowly.
Highway Driving
Tires
Adjust the tire inflation, as specified.
Under-inflation may overheat or damage
the tires.
Do not install worn-out or damaged tires,
which may reduce traction or adversely
affect vehicle handling. This could lead
to sudden tire failure that may cause
loss of vehicle control resulting in an
accident.
Information
Never over-inflate your tires above the
maximum inflation pressure, as specified
on your tires.
Fuel, engine coolant and engine oil
Driving at higher speeds on the highway
consumes more fuel and is less efficient
than driving at a slower, more moderate
speed. Maintain a moderate speed in
order to conserve fuel when driving on
the highway.
Be sure to check both the engine coolant
level and the engine oil before driving.
Drive belt
A loose or damaged drive belt may
overheat the engine.

06
6-137
Chain installation
When installing tire chains, follow the
manufacturer’s instructions and mount
them as tightly possible. Drive slowly
(less than 20 mph (30 km/h)) with
chains installed. If you hear the chains
contacting the body or chassis, stop and
tighten them. If they still make contact,
slow down until the noise stops. Remove
the tire chains as soon as you begin
driving on cleared roads.
When mounting snow chains, park the
vehicle on level ground away from traffic.
Turn on the vehicle Hazard Warning
Flasher and place a triangular emergency
warning device behind the vehicle (if
available). Always place the vehicle in P
(Park), apply the parking brake and turn
off the engine before installing snow
chains.
NOTICE
When using tire chains:
• Wrong size chains or improperly
installed chains can damage your
vehicle's brake lines, suspension,
body and wheels.
• Use SAE "S" class or wire chains.
• If you hear noise caused by chains
contacting the body, retighten the
chain to prevent contact with the
vehicle body.
• To prevent body damage, retighten
the chains after driving 0.3~0.6 miles
(0.5~1.0 km).
• Do not use tire chains on vehicles
equipped with aluminum wheels. If
unavoidable, use a wire type chain.
• Use wire chains less than 0.59 inch
(15mm) wide to prevent damage to
the chain’s connection.
Winter Precautions
Use high quality ethylene glycol
coolant
Your vehicle is delivered with high
quality ethylene glycol coolant in the
cooling system. It is the only type of
coolant that should be used because it
helps prevent corrosion in the cooling
system, lubricates the water pump and
prevents freezing. Be sure to replace or
replenish your coolant in accordance
with the maintenance schedule in
chapter 8. Before winter, have your
coolant tested to assure that its freezing
point is sufficient for the temperatures
anticipated during the winter.
Change to "winter weight" oil if
necessary
In some climates it is recommended that
a lower viscosity "winter weight" oil be
used during cold weather. See chapter 8
for recommendations. If you aren't sure
what weight oil you should use, consult
an authorized HYUNDAI dealer.
Check battery and cables
Winter puts additional burdens on the
battery system. Visually inspect the
battery and cables as described in
chapter 8. The level of charge in your
battery can be checked by an authorized
HYUNDAI dealer or a service station.

While Driving
6-138
Check spark plugs and ignition
system
Inspect your spark plugs as described in
chapter 8 and replace them if necessary.
Also check all ignition wiring and
components to be sure they are not
cracked, worn or damaged in any way.
Use approved window washer anti-
freeze in system
To keep the water in the window washer
system from freezing, add an approved
window washer anti-freeze solution in
accordance with instructions on the
container. Window washer anti-freeze is
available from an authorized HYUNDAI
dealer and most auto parts outlets. Do
not use engine coolant or other types
of antifreeze as these may damage the
paint finish.
Do not let your parking brake freeze
Under some conditions your parking
brake can freeze in the engaged position.
This is most likely to happen when
there is an accumulation of snow or
ice around or near the rear brakes or
if the brakes are wet. If there is a risk
the parking brake may freeze, apply
it only temporarily while you put the
gear selector lever in P and block the
rear wheels so the car cannot roll. Then
release the parking brake.
Do not let ice and snow accumulate
underneath
Under some conditions, snow and ice
can build up under the fenders and
interfere with the steering. When driving
in severe winter conditions where this
may happen, you should periodically
check underneath the car to be sure the
movement of the front wheels and the
steering components is not obstructed.
Don't place foreign objects
or materials in the engine
compartment
Placement of foreign object or materials
which prevent cooling of the engine, in
the engine compartment, may cause a
failure or combustion. The manufacturer
is not responsible for the damage caused
by such placement.
To keep locks from freezing
To keep the locks from freezing, squirt
an approved de-icer fluid or glycerine
into the key opening. If a lock is covered
with ice, squirt it with an approved de-
icing fluid to remove the ice. If the lock
is frozen internally, you may be able to
thaw it out by using a heated key. Handle
the heated key with care to avoid injury.

07
7-7
If your temperature gauge indicates
overheating, you experience a loss of
power, or hear loud pinging or knocking,
the engine may be overheating. If this
happens, you should:
1. Pull off the road and stop as soon as it
is safe to do so.
2. Shift the gear to P (Park) and set the
parking brake
3. Turn off the air conditioner.
4. When the coolant or hot steams
gush out of the reservoir, stop the
engine and we recommend that
you call an authorized HYUNDAI
dealer for assistance. If the coolant
does not flow out, leave the engine
compartment opened, while running
the engine. Check the coolant
temperature gauge on the instrument
cluster and turn off the engine to
make sure the coolant temperature is
sufficiently cooled down.
5. Cool down the engine sufficiently
and check the coolant level. When it
is insufficient, check its connection
with the radiator, the heater hose,
and the water pump for any leakage.
When there is no leakage, add the
coolant. However, if the problems
persists, such as the coolant leakages,
the cooling-fan malfunction or the
water pump drive belt damages,
immediately stop the engine, and
have your vehicle checked by an
authorized HYUNDAI dealer.
• You should mix antifreeze and water in
a proper ratio to make coolant. If the
antifreeze ratio is too high or low, it
may cause overheating due to the lack
of cooling function.
(Refer to the Mix Ratio in “Checking
the coolant level” in chapter 8.)
• If overheating happens repeatedly,
we recommend that you have
your vehicle to be checked by an
authorized HYUNDAI dealer.
WARNING
While the engine is running, keep hands, clothing and tools
away from the moving parts
such as the cooling fan and
drive belt to prevent serious
injury.
IF THE ENGINE OVERHEATS

Emergency situations
7-8
WARNING
Never remove the engine coolant cap and/or inverter
coolant cap or the drain plug
while the engine and radiator
are hot.
Hot coolant and steam may blow out
under pressure, causing serious injury.
Turn the hybrid system off and wait until
the engine cools down. Use extreme
care when removing the engine coolant
cap and/or inverter coolant 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
counterclockwise to remove it.
CAUTION
• Serious loss of coolant indicates a
leak in the cooling system and should
be checked as soon as possible by an
authorized HYUNDAI dealer.
• When the engine overheats from
low engine coolant, suddenly adding
engine coolant may cause cracks
in the engine. To prevent damage,
add engine coolant slowly in small
quantities.

8. Maintenance
Engine Compartment ........................................................................\
...............8-3
Maintenance Services
........................................................................\
..............8-4Owner’s Responsibility ........................................................................\
.......................8-4
Owner Maintenance Precautions ........................................................................\
.......8-4
Owner Maintenance ........................................................................\
.................8-5Owner Maintenance Schedule ........................................................................\
............8-5
Scheduled Maintenance Services ....................................................................8 -7Normal Maintenance Schedule ........................................................................\
..........8-8
Maintenance Under Severe Usage Conditions .........................................................8-11
Explanation of Scheduled Maintenance Items ..............................................8-13
Engine Oil
........................................................................\
.................................8-15Checking the Engine Oil Level ........................................................................\
...........8-15
Checking the Engine Oil and Filter ........................................................................\
...8-16
Engine Coolant/Inverter Coolant ....................................................................8-17Checking the Coolant Level ........................................................................\
................ 8-17
Changing Coolant ........................................................................\
..............................8-19
Hybrid Starter & Generator (HSG) Belt ..........................................................8-20Checking the Hybrid Starter & Generator (HSG) Belt .............................................8-20
Brake Fluid ........................................................................\
...............................8-20Checking the Brake Fluid Level ........................................................................\
........8-20
Washer Fluid ........................................................................\
.............................8-21Checking the Washer Fluid Level ........................................................................\
......8-21
Air Cleaner ........................................................................\
...............................8-22Filter Replacement ........................................................................\
.............................8-22
Cabin Air Filter ........................................................................\
.........................8-23Filter Inspection ........................................................................\
.................................. 8-23
Filter Replacement ........................................................................\
.............................8-23
Wiper Blades ........................................................................\
...........................8-24Blade Inspection ........................................................................\
................................8-24
Blade Replacement
........................................................................\
............................8-24
Maintenance
8

8-3
08
„„Smartstream G2.0 GDi HEV
The actual engine compartment in the vehicle may differ from the illustration.
ODN8H089001
1. Engine coolant reservoir
2. Engine coolant reservoir cap
3. Inverter coolant reservoir
4. Brake fluid reservoir
5. Air cleaner
6. Engine oil dipstick
7. Engine oil filler cap
8. Windshield washer fluid reservoir
9. Fuse box
ENGINE COMPARTMENT