2021 HYUNDAI SONATA HYBRID engine

08
8-5
WARNING
Performing maintenance work on a
vehicle can be dangerous. If you lack
sufficient knowledge and experience or
the proper tools and equipment to do
the work, have it done by an authorized
HYUNDAI dealer.
ALWAYS follow these precautions for
performing maintenance work:
• Park your vehicle on level ground,
shift the gear to P (Park), apply
the parking brake, and press the
Engine Start/Stop button to the OFF
position.
• Block the tires (front and back) to
prevent the vehicle from moving.
Remove loose clothing or jewelry
that can become entangled in
moving parts.
• If you must run the engine during
maintenance, do so out doors or in
an area with plenty of ventilation.
• Keep flames, sparks, or smoking
materials away from the battery and
fuel-related parts. The following lists are vehicle checks and
inspections that should be performed
by the owner or an authorized HYUNDAI
dealer at the frequencies indicated to
help ensure safe, dependable operation
of your vehicle.
Any adverse conditions should be
brought to the attention of your dealer as
soon as possible.
These Owner Maintenance vehicle
checks are generally not covered by
warranties and you may be charged for
labor, parts and lubricants used.
Owner Maintenance Schedule
When you stop for fuel:
•
Check the engine oil level.
• Check the coolant level in the engine
coolant reservoir.
• Check the windshield washer fluid
level.
• Check for low or under-inflated tires.
WARNING
Be careful when checking your engine
coolant/inverter coolant level when the
engine is hot. This may result in coolant
being blown out of the opening and
cause serious burns and other injuries.
OWNER MAINTENANCE

Maintenance
8-6
While operating your vehicle:
• Note any changes in the sound of the
exhaust or any smell of exhaust fumes
in the vehicle.
• Check for vibrations in the steering
wheel. Notice if there is any increased
steering effort or looseness in the
steering wheel, or change in its
straight-ahead position.
• Notice if your vehicle constantly turns
slightly or “pulls” to one side when
traveling on smooth, level road.
• When stopping, listen and check for
unusual sounds, pulling to one side,
increased brake pedal travel or “hard-
to-push” brake pedal.
• If any slipping or changes in the
operation of your transmission occurs,
check the transmission fluid level.
• Check the automatic transmission P
(Park) function.
• Check the parking brake.
• Check for fluid leaks under your
vehicle (water dripping from the air
conditioning system during or after
use is normal).
At least monthly:
• Check coolant level in the engine
coolant reservoir.
• Check the operation of all exterior
lights, including the stoplights, turn
signals and hazard warning flashers.
• Check the inflation pressures of all
tires including the spare for tires that
are worn, show uneven wear, or are
damaged.
• Check for loose wheel lug nuts.
At least twice a year: (i.e., every
Spring and Autumn)
• Check radiator, heater and air
conditioning hoses for leaks or
damage.
• Check windshield washer spray and
wiper operation. Clean wiper blades
with a clean cloth dampened with
washer fluid.
• Check headlamp alignment.
• Check muffler, exhaust pipes, shields
and clamps.
• Check the seat belts for wear and
function.
At least once a year:
• Clean body and door drain holes.
• Lubricate door hinges and hood
hinges.
• Lubricate door and hood locks and
latches.
• Lubricate door rubber weather strips.
• Check the air conditioning system.
• Inspect and lubricate automatic
transmission linkage and controls.
• Clean the battery and terminals.
• Check the brake fluid level.

08
8 -7
Follow Normal Maintenance Schedule if the vehicle is usually operated where none of
the following conditions apply. If any of the following conditions apply, you must follow
the Maintenance Under Severe Usage Conditions.
• Repeated driving short distance of less than 5 miles (8 km) in normal temperature or
less than 10 miles (16 km) in freezing temperature
• Extensive engine idling or low speed driving for long distances
• Driving on rough, dusty, muddy, unpaved, graveled or salt-spread roads
• Driving in areas using salt or other corrosive materials or in very cold weather
• Driving in heavy dust conditions
• Driving in heavy traffic area
• Driving on uphill, downhill, or mountain road repeatedly
• Towing a trailer or using a camper, or roof rack
• Driving as a patrol car, taxi, other commercial use of vehicle towing
• Driving over 106 mph (170 km/h)
• Frequently driving in stop-and-go condition
If your vehicle is operated under the above conditions, you should inspect, replace
or refill more frequently than the following Normal Maintenance Schedule. After the
periods or distance shown in the chart, continue to follow the prescribed maintenance
intervals.
SCHEDULED MAINTENANCE SERVICES

Maintenance
8-8
Normal Maintenance ScheduleThe following maintenance services must be performed to ensure good emission control and performance.
Keep receipts for all vehicle emission services to protect your warranty. Where both mileage and time are shown, the frequency of
service is determined by whichever occurs first.
MAINTENANCE

INTERVALS
MAINTENANCE
ITEM Number of months or driving distance, whichever comes first
Months 1224 3648 60 7284 96108 120 132144 156168 180
Miles 7. 51522.5 3037.5 4552.5 6067.5 7583 90 98105 113
Km 1224 3648 60 7284 96108 120 132144 156168 180
HSG belts
*1
Inspect every 7,500 miles or 12 months,
and replace every 67,500 miles or 48 months
Engine oil and engine oil filter RRRRRRRRRRRRRRR
Fuel additives
*2
Add fuel additives every 7,500 miles or 12 months
Air cleaner filter IIIR IIIR IIIR III
Spark plugs Replace every 100,000miles
Rotate tires Rotate tires every 7,500 miles
Climate control air filter Replace every 15,000 miles or 12 months
Vacuum hose IIIIIIIIIIIIIII
Engine coolant / Inverter coolant At first, replace at 120,000 miles or 10 years :
after that, replace every 30,000 miles or 24 months
I : Inspect and if necessary, adjust, correct, clean or replace.
R : Replace or change.*1 : The drive belt should be replaced when cracks occur or tension is reduced excessively.
*2 : If TOP TIER Detergent Gasoline is not available, one bottle of additive is recommended. Additives are available from your
authorized HYUNDAI dealer along with information on how to use them. Do not mix other additives.

08
8-11
Maintenance Under Severe Usage Conditions
The following items must be serviced more frequently on cars normally used under severe
driving conditions. Refer to the chart below for the appropriate maintenance intervals.
R : Replace
I : Inspect and, after inspection, clean, adjust, repair or replace if necessary
Maintenance ItemMaintenance
operation Maintenance Intervals Driving
condition
HSG (Hybrid Starter &
Generator) belt R
Every 30,000 miles (48,000 km)
or 24 months C, D, E, I
I Every 3,750 miles (6,000 km) or
6 months
Engine oil and filter REvery 3,750 miles (6,000 km) or
6 months A, B, C, D, E,

F, G, H, I, K
Air cleaner filter RMore frequently C, E
Spark plugs RMore frequently B, H
Climate control air filter
(for evaporator and
blower unit) R
More frequently C, E
Front brake disc/pads,
calipers I
More frequently C, D, G, H

Maintenance
8-12
Maintenance ItemMaintenance
operation Maintenance Intervals Driving
condition
Rear brake disc/pads IMore frequently C, D, G, F
Steering gear box,
linkage & boots/ lower
arm ball joint, upper arm
ball joint I
More frequently C, D, E, F, G,
H, I
Drive shafts and boots IEvery 7,500 miles (12,000 km) or
6 months C, D, E, F,
G, H, I, J
Automatic transmission
fluid R
Every 60,000 miles (96,000 km) A, C, D, E, F,

G, H, I, K
Parking brake IMore frequently C, D, G, H
Severe driving conditions
A. Repeatedly driving short distance of less than 5 miles (8 km) in normal temperature
or less than 10 miles (16 km) in freezing temperature
B. Extensive engine idling or low speed driving for long distances
C. Driving on rough, dusty, muddy, unpaved, graveled or saltspread roads
D. Driving in areas using salt or other corrosive materials or in very cold weather
E. Driving in sandy areas
F. Driving in heavy traffic area over 90°F (32°C)
G. Driving on uphill, downhill, or mountain road
H. Towing a Trailer, or using a camper, or roof rack
I. Driving as a patrol car, taxi, other commercial use or vehicle towing
J. Driving over 106 mph (170 km/h)
K. Frequently driving in stop-and-go conditions

08
8-13
Engine Oil and Filter
The engine oil and filter should be
changed at the intervals specified in the
maintenance schedule. If the vehicle
is being driven in severe conditions,
more frequent oil and filter changes are
required.
HSG (Hybrid Starter & Generator)
Belt
The HSG belt should be changed at the
intervals specified in the maintenance
schedule.
Fuel Lines, Fuel Hoses and
Connections
Check the fuel lines, fuel hoses and
connections for leakage and damage.
Have an authorized HYUNDAI dealer
replace any damaged or leaking parts
immediately.
Fuel Filter
A clogged filter can limit the speed
at which the vehicle may be driven,
damage the emission system and cause
multiple issues such as hard starting. If
an excessive amount of foreign matter
accumulates in the fuel tank, the
filter may require replacement more
frequently. After installing a new filter,
run the engine for several minutes,
and check for leaks at the connections.
Fuel filters should be installed by an
authorized HYUNDAI dealer.
Vapor Hose and Fuel Filler Cap
The vapor hose and fuel filler cap should
be inspected at those intervals specified
in the maintenance schedule. Make sure
a new vapor hose or fuel filler cap is
correctly replaced.
Air Cleaner Filter
A genuine HYUNDAI air cleaner filter
is recommended when the filter is
replaced.
Spark Plugs
Make sure to install new spark plugs of
the correct heat range.
Cooling System
Check cooling system components, such
as radiator, coolant reservoir, hoses and
connections for leakage and damage.
Replace any damaged parts.
Engine Coolant/Inverter Coolant
The coolant should be changed at the
intervals specified in the maintenance
schedule.
Automatic Transmission Fluid
Automatic transmission fluid should
not be checked under normal usage
conditions. But in severe conditions, the
fluid should be changed at an authorized
HYUNDAI dealer in accordance to the
scheduled maintenance at the beginning
of this chapter.
EXPLANATION OF SCHEDULED MAINTENANCE ITEMS

Maintenance
8-14
Information
Automatic transmission fluid color is red
when new.
As the vehicle is driven, the automatic
transmission fluid will begin to look
darker. This is a normal condition and you
should not judge the need to replace the
fluid based upon the changed color.
NOTICE
The use of a non-specified fluid could
result in transmission malfunction
and failure. Use only the specified
automatic transmission fluid (refer
to “Recommended Lubricants and
Capacities” in chapter 2).
Engine Clutch Actuator Fluid
The engine clutch actuator fluid level
should be inspected or replaced to the
intervals specified in the maintenance
schedule.
Brake Hoses and Lines
Visually check for proper installation,
chafing, cracks, deterioration and any
leakage. Replace any deteriorated or
damaged parts immediately.
Brake Fluid
Check the brake fluid level in the brake
fluid reservoir. The level should be
between the MIN and the MAX marks
on the side of the reservoir. Use only
hydraulic brake fluid conforming to DOT
4 specification.
Parking Brake
Inspect the parking brake system.
Brake Discs, Pads, Calipers and
Rotors
Check the pads, the disc, and the rotor
for any excessive wear-out. Inspect
calipers for any fluid leakage
Exhaust Pipe and Muffler
Visually inspect the exhaust pipes,
muffler and hangers for cracks,
deterioration, or damage. Start
the engine and listen carefully for
any exhaust gas leakage. Tighten
connections or replace parts as
necessary.
Suspension Mounting Bolts
Check the suspension connections for
looseness or damage. Retighten to the
specified torque.
Steering Gear Box, Linkage &
Boots/Lower Arm Ball Joint
With the vehicle stopped and the hybrid
system off, check for excessive free-play
in the steering wheel. Check the linkage
for bends or damage. Check the dust
boots and ball joints for deterioration,
cracks, or damage.
Replace any damaged parts.
Drive Shafts and Boots
Check the drive shafts, boots and clamps
for cracks, deterioration, or damage.
Replace any damaged parts and, if
necessary, repack the grease.
Air Conditioning Refrigerant
Check the air conditioning lines and
connections for leakage and damage.