2021 HYUNDAI SONATA HYBRID fuel

F2
This manual includes information titled as DANGER, WARNING, CAUTION and
NOTICE.
These titles indicate the following:
DANGER
DANGER indicates a hazardous situation which, if not avoided, will result in
death or serious injury.
WARNING
WARNING indicates a hazardous situation which, if not avoided, could result
in death or serious injury.
CAUTION
CAUTION indicates a hazardous situation which, if not avoided, could result
in minor or moderate injury.
NOTICE
NOTICE indicates a situation which, if not avoided, could result in vehicle
damage.
Your HYUNDAI should not be modified in any way. Such modifications may
adversely affect the performance, safety or durability of your HYUNDAI
and may, in addition, violate conditions of the limited warranties covering
the vehicle. Certain modifications may also be in violation of regulations
established by the U.S. Department of Transportation and other federal or state
agencies.
Your vehicle is equipped with electronic fuel injection and other electronic
components. It is possible for an improperly installed/adjusted two-way radio
or cellular telephone to adversely affect electronic systems. For this reason,
we recommend that you carefully follow the radio manufacturer’s instructions
or consult your HYUNDAI dealer for precautionary measures or special
instructions if you choose to install one of these devices.
CAUTION: MODIFICATIONS TO YOUR HYUNDAI
TWO-WAY RADIO OR CELLULAR TELEPHONE INSTALLATION
SAFETY AND VEHICLE DAMAGE WARNING

Introduction........................................................................\
................................1-2
Hyundai Motor America
........................................................................\
............1-2
Guide to Hyundai Genuine Parts
......................................................................1-3
How to Use This Manual
........................................................................\
............1-4
Safety Messages
........................................................................\
........................1-4
Fuel Requirements
........................................................................\
.....................1-5
Vehicle Modifications
........................................................................\
................1 -7
Vehicle Break-In Process
........................................................................\
...........1 -7
Vehicle Data Collection and Event Data Recorders
........................................1-8
California Perchlorate Notice
........................................................................\
....1-9
Consumer Information
........................................................................\
............1-10
Reporting Safety Defects
........................................................................\
.........1-11
HEV (Hybrid Electric Vehicle) System
.............................................................1-12
Driving the Hybrid Vehicle
........................................................................\
.......1-13Starting the Vehicle ........................................................................\
.............................1-13
Special Features ........................................................................\
..................................1-13
Hybrid System Gauge
........................................................................\
.........................1-15
Warning and Indicator Lights ........................................................................\
.............1-16
LCD Display Messages ........................................................................\
........................1-17
Energy Flow ........................................................................\
........................................1-20
Safety Precautions for Hybrid System ............................................................1-23Hybrid Vehicle Components ........................................................................\
..............1-23
Service Interlock Connector ........................................................................\
...............1-25
Hybrid Battery Cooling Duct ........................................................................\
..............1-25
If an Accident Occurs ........................................................................\
.........................1-26
When the Hybrid Vehicle Shuts Off ........................................................................\
...1-27
Foreword
1. Foreword / Hybrid System
Overview
1

Foreword
1-2
INTRODUCTION
Congratulations, and thank you for choosing HYUNDAI. We are pleased to welcome
you to the growing number of discerning people who drive HYUNDAIs. We are very
proud of the advanced engineering and high-quality construction of each HYUNDAI
we build.
Your Owner’s Manual will introduce you to the features and operation of your new
HYUNDAI. To become familiar with your new HYUNDAI, so that you can fully enjoy it,
read this Owner’s Manual carefully before driving your new vehicle.
This manual contains important safety information and instructions intended to
familiarize you with your vehicle’s controls and safety features so you can safely
operate your vehicle.
This manual also contains information on maintenance designed to enhance safe
operation of the vehicle. It is recommended that all service and maintenance on your
car be performed by an authorized HYUNDAI dealer. HYUNDAI dealers are prepared
to provide high-quality service, maintenance and any other assistance that may be
required.
This Owner’s Manual should be considered a permanent part of your vehicle, and
should be kept in the vehicle so you can refer to it at any time. The manual should stay
with the vehicle if you sell it to provide the next owner with important operating, safety
and maintenance information.
HYUNDAI MOTOR AMERICA
CAUTION
Severe engine and transmission damage may result from the use of poor quality
fuels and lubricants that do not meet HYUNDAI specifications. You must always use
high quality fuels and lubricants that meet the specifications listed on Page 2-11 in
the Vehicle Specifications section of the Owner’s Manual.
Copyright 2020 HYUNDAI Motor America. All rights reserved. No part of this
publication may be reproduced, stored in any retrieval system or transmitted in
any form or by any means without the prior written permission of HYUNDAI Motor
America.

01
1-5
Your new vehicle is designed to obtain
maximum performance with UNLEADED
FUEL, as well as minimize exhaust
emissions and spark plug fouling.
Your new vehicle is designed to use only
unleaded fuel having an octane number
((R+M)/2) of 87 (Research Octane
Number 91) or higher. (Do not use
methanol blended fuels)
NOTICE
To prevent damage to the engine and
engine components, never add any fuel
system cleaning agents to the fuel tank
other than what has been specified.
Consult an authorized HYUNDAI dealer
for additional information.
WARNING
• Do not “top off” after the nozzle
automatically shuts off when
refueling.
• Always check that the fuel cap is
installed securely to prevent fuel
spillage in the event of an accident.
FUEL REQUIREMENTS
Throughout this manual DANGER,
WARNING, CAUTION, NOTICE and the
SAFETY ALERT SYMBOL will be used.
This is the safety alert symbol. It is used to alert you to potential
physical injury hazards. Obey
all safety messages that follow
this symbol to avoid possible
injury or death. The safety alert
symbol precedes the signal
words DANGER, WARNING and
CAUTION.
DANGER
DANGER indicates a hazardous
situation which, if not avoided, will
result in death or serious injury.
WARNING
WARNING indicates a hazardous
situation which, if not avoided, could
result in death or serious injury.
CAUTION
CAUTION indicates a hazardous
situation which, if not avoided, could
result in minor or moderate injury.
NOTICE
NOTICE indicates a situation which,
if not avoided, could result in vehicle
damage.

Foreword
1-6
Gasoline containing alcohol or
methanol
Gasohol, a mixture of gasoline and
ethanol (also known as grain alcohol) are
being marketed along with or instead
of leaded or unleaded gasoline. For
example, “E15” is a gasohol comprised of
15% ethanol and 85% gasoline.
Do not use gasohol containing more than
15% ethanol, and do not use gasoline or
gasohol containing any methanol. Either
of these fuels may cause drivability
problems and damage to the fuel
system, engine control system and
emission control system.
Discontinue using gasohol of any kind if
drivability problems occur.
“E85” fuel is an alternative fuel
comprised of 85 percent ethanol and 15
percent gasoline, and is manufactured
exclusively for use in Flexible Fuel
Vehicles. “E85” is not compatible with
your vehicle. Use of “E85” may result in
poor engine performance and damage
to your vehicle’s engine and fuel system.
HYUNDAI recommends that customers
do not use fuel with an ethanol content
exceeding 15 percent.
NOTICE
To prevent damage to your vehicle’s
engine and fuel system:
• Never use gasohol which contains
methanol.
• Never use gasohol containing more
than 15% ethanol.
• Never use leaded fuel or leaded
gasohol.
• Never use “E85” fuel.
Your New Vehicle Limited Warranty
does not cover damage to the fuel
system or any performance problems
caused by the use of “E85” fuel.
Using Fuel Additives (except
Detergent Fuel Additives)
Using fuel additives such as:
- Silicone fuel additive
-Ferrocene (iron-based) fuel additive
-Other metallic-based fuel additives
may result in cylinder misfire, poor
acceleration, engine stalling, damage
to the catalyst, or abnormal corrosion,
and may cause damage to the engine
resulting in a reduction in the overall life
of the powertrain.
- The Malfunction Indicator Lamp (MIL)
may illuminate.
NOTICE
Damage to the fuel system or
performance problem caused by the
use of these fuels or fuel additives may
not be covered by your New Vehicle
Limited Warranty.
Gasoline containing MMT
Some gasoline contains harmful
manganese-based fuel additives such
as MMT (Methylcyclopentadienyl
Manganese Tricarbonyl).
HYUNDAI does not recommend the use
of gasoline containing MMT.
This type of fuel can reduce vehicle
performance and affect your emission
control system.
The malfunction indicator lamp on the
cluster may come on.

01
1 -7
Detergent Fuel Additives
HYUNDAI recommends that you use
good quality gasolines treated with
detergent additives such as TOP TIER
Detergent Gasoline, which help prevent
deposit formation in the engine. These
gasolines will help the engine run
cleaner and enhance performance of
the Emission Control System. For more
information on TOP TIER Detergent
Gasoline, please go to the website (www.
toptiergas.com ).
For customers who do not use TOP Tier
Detergent Gasoline regularly, and have
problems starting or the engine does
not run smoothly, detergent-based
fuel additives that you can purchase
separately may be added to the gasoline.
If TOP TIER Detergent Gasoline is
not available, one bottle of additive
added to the fuel tank according to the
maintenance schedule is recommended
(refer to the Maintenance Schedule in
chapter 8).
Additives are available from your
authorized HYUNDAI dealer along with
information on how to use them. Do not
mix other additives.
Operation in foreign countries
If you are going to drive your vehicle in
another country, be sure to:
• Observe all regulations regarding
registration and insurance.
• Determine that acceptable fuel is
available. •
This vehicle should not be modified.
Modification of your vehicle could
affect its performance, safety or
durability and may even violate
governmental safety and emissions
regulations.
In addition, damage or performance
problems resulting from any
modification may not be covered
under warranty.
• If you use unauthorized electronic
devices, it may cause the vehicle to
operate abnormally, wire damage,
battery discharge and fire. For your
safety, do not use unauthorized
electronic devices.
VEHICLE BREAK-IN
PROCESS
By following a few simple precautions for
the first 600 miles (1,000 km) you may
add to the performance, economy and
life of your vehicle.
• Do not race the engine.
• While driving, keep your engine speed
(rpm, or revolutions per minute)
between 2,000 rpm and 4,000 rpm.
• Do not maintain a single speed for
long periods of time, either fast or
slow. Varying engine speed is needed
to properly break-in the engine.
• Avoid hard stops, except in
emergencies, to allow the brakes to
seat properly.
VEHICLE MODIFICATIONS

1-12
Foreword
HEV (HYBRID ELECTRIC VEHICLE) SYSTEM
The HYUNDAI Hybrid Electric Vehicle (HEV) uses both the gasoline engine and the
electric motor for power. The electric motor is run by a high-voltage HEV battery.
Depending on the driving conditions, the HEV computer selectively operates between
the engine and the electric motor or even both at the same time.
Fuel efficiency increases when the engine is at idle, or when the vehicle is driven by the
electric motor with the HEV battery.
The HEV battery charge must be maintained, so at times the engine will come on even
at idle to act as a generator. Charging also occurs when decelerating or by regenerative
braking.
Electric motorElectric motorElectric motor + EngineElectric motor + Engine EngineEngineChargingCharging Engine OFFEngine OFF
Startup/Low speed cruise Acceleration High speed cruiseDecelerationStop
ODN8H069105

01
1-15
Hybrid System Gauge
Power gauge
„„Type A, B
ODN8H049032
„„Type C
ODN8H040033N
The hybrid system gauge indicates
whether the current driving condition is
fuel efficient or not.
• CHARGE:
Shows that the energy made by the
vehicle is being converted to electrical
energy. (Regenerated energy)
• ECO:
Shows that the vehicle is being driven
in an Eco-friendly manner.
• POWER:
Shows that the vehicle is exceeding
the Eco-friendly range.
According to the hybrid system gauge
area, the “EV” indicator comes on or off.
- “EV” indicator ON : Vehicle is driven
using the electric motor or the
gasoline engine is stopped.
-“EV” indicator OFF : Vehicle is driven
using the gasoline engine.
Hybrid battery SOC (State of Charge)
gauge
„„Type A, B
ODN8H049034
„„Type C
ODN8H040035N
This gauge indicates the remaining
hybrid battery power. If the SOC is
near the “L (Low)” level, the vehicle
automatically operates the engine to
charge the battery.
However, if the Service Indicator (
)
and Malfunction Indicator Lamp (MIL)
(
) turn on when the SOC gauge is near
the “L (Low)” level, we recommend the
vehicle be checked by an authorized
HYUNDAI dealer.