Fuel system HYUNDAI NEXO 2021 User Guide

6-4
If you have a flat tire while
driving
If a tire goes flat while you are driv-
ing:
1. Take your foot off the accelerator
pedal and let the vehicle slow
down while driving straight ahead.
Do not apply the brakes immedi-
ately or attempt to pull off the road
as this may cause a loss of con-
trol. When the vehicle has slowed
to such a speed that it is safe to do
so, brake carefully and pull off the
road. Drive off the road as far as
possible and park on firm, level
ground. If you are on a divided
highway, do not park in the medi-
an area between the two traffic
lanes.
2. When the vehicle is stopped, turn
on your emergency hazard flash-
ers, set the parking brake and shift
gear to the P(Park) position.
3. Have all passengers get out of the
vehicle. Be sure they all get out on
the side of the vehicle that is away
from traffic.
If the vehicle stalls while driv-
ing
1. Reduce your speed gradually,
keeping a straight line. Move cau-
tiously off the road to a safe place.
2. Turn on your emergency flashers.
3. Try to start the vehicle again. If
your vehicle will not start, contact
an authorized HYUNDAI dealer. Be sure the shift lever is in P
(Park). The vehicle starts only
when the shift lever is in P (Park).
This vehicle does not have a regu-
lar 12V battery that needs periodic
replacement. It is lithium ion poly-
mer type integrated into the high
voltage battery. The vehicle has a
12V battery protection system that
cuts 12V battery from vehicle draw
to prevent full discharge. If vehicle
will not start, first try pressing the
12V Battery Reset switch (left side
of the steering wheel near the fuel
door open switch) to reconnect the
12V battery, but you must start
vehicle within 15 seconds of press-
ing the 12V Battery Reset switch.
After starting vehicle, operate the
vehicle safely outdoors in ready
mode stopped and/or drive it for 30
minutes total to charge the 12V
battery fully.
Check the fuel level and add fuel if
necessary.
Do not push or pull the vehicle to
start it.
If the vehicle still does not start, call
an authorized HYUNDAI dealer for
assistance.
What to do in an emergency
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6-6
What to do in an emergency
The following items may need to be
reset after the battery has been dis-
charged or the battery has been dis-
connected. See chapter 3 or 4 for:
Power Windows
Trip Computer
Climate Control System
Clock
Audio System
Sunroof
Driver Position Memory System
External power source using 12V
battery
The use of external power acces-
sories may reduce performance
and function of the vehicle.
Especially, the use of dash cam-
eras may shut off the power of the
vehicle prior to the dash camera's
automatic shut-down.
If the power of the vehicle is shut
off, start the vehicle as explained.
(refer to "Using the 12V Battery
Switch")
Jump Starting
In the event vehicle still does not
have a functional 12V battery (check
if interior lights will not turn on) then
you can try a jump start using a 12V
booster pack or jumper cables from
another vehicle's 12V battery
according to the following instruc-
tions.1. Position the vehicles close enough
that the jumper cables will reach,
but do not allow the vehicles to
touch.
2. Avoid fans or any moving parts in
the fuel cell power module com-
partment at all times, even when
the vehicles are turned off.
3. Turn off all electrical devices such
as radios, lights, air conditioning,
etc. Put the vehicles in P (Park)
and set the parking brake. Turn
both vehicles OFF.
NOTICE
Jump starting can be danger-
ous if done incorrectly. Follow
the jump starting procedure in
this section to avoid serious
injury or damage to your vehi-
cle. If in doubt about how to
properly jump start your vehi-
cle, we strongly recommend
that you have a service techni-
cian or towing service do it for
you.
CAUTION

6-12
What to do in an emergency
Tire Pressure Monitoring
System
Each tire, including the spare (if pro-
vided), should be checked monthly
when cold and inflated to the inflation
pressure recommended by the vehi-
cle manufacturer on the vehicle plac-
ard or tire inflation pressure label. If
your vehicle has tires of a different
size than the size indicated on the
vehicle placard or tire inflation pres-
sure label, you should determine the
proper tire inflation pressure for
those tires.As an added safety feature, your
vehicle has been equipped with a tire
pressure monitoring system (TPMS)
that illuminates a low tire pressure
telltale when one or more of your
tires is significantly under-inflated.
Accordingly, when the low tire pres-
sure telltale illuminates, you should
stop and check your tires as soon as
possible, and inflate them to the
proper pressure. Driving on a signifi-
cantly under-inflated tire causes the
tire to overheat and can lead to tire
failure.
Under-inflation also reduces fuel effi-
ciency and tire tread life, and may
affect the vehicle's handling and
stopping ability.
Please note that the TPMS is not a
substitute for proper tire mainte-
nance, and it is the driver's responsi-
bility to maintain correct tire pres-
sure, even if under-inflation has not
reached the level to trigger illumina-
tion of the TPMS low tire pressure
telltale.Your vehicle has also been equipped
with a TPMS malfunction indicator to
indicate when the system is not
operating properly. The TPMS mal-
function indicator is combined with
the low tire pressure telltale. When
the system detects a malfunction,
the telltale will flash for approximate-
ly one minute and then remain con-
tinuously illuminated. This sequence
will continue upon subsequent vehi-
cle start-ups as long as the malfunc-
tion exists.
When the malfunction indicator is
illuminated, the system may not be
able to detect or signal low tire pres-
sure as intended. TPMS malfunc-
tions may occur for a variety of rea-
sons, including the installation of
replacement or alternate tires or
wheels on the vehicle that prevent
the TPMS from functioning properly.
Always check the TPMS malfunction
telltale after replacing one or more
tires or wheels on your vehicle to
ensure that the replacement or alter-
nate tires and wheels allow the TPMS
to continue to function properly. Over-inflation or under-inflation
can reduce tire life, adversely
affect vehicle handling, and
lead to sudden tire failure that
may cause loss of vehicle con-
trol resulting in an accident.
WARNING

7-4
Maintenance
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You should exercise the utmost care
to prevent damage to your vehicle
and injury to yourself whenever per-
forming any maintenance or inspec-
tion procedures.
We recommend you have your vehi-
cle maintained and repaired by an
authorized HYUNDAI dealer. An
authorized HYUNDAI dealer meets
HYUNDAI's high service quality
standards and receives technical
support from HYUNDAI in order to
provide you with a high level of serv-
ice satisfaction.Owner's Responsibility
Maintenance service and record
retention are the owner's responsibil-
ity.
You should retain documents that
show proper maintenance has been
performed on your vehicle in accor-
dance with the scheduled mainte-
nance service charts shown on the
following pages. You need this infor-
mation to establish your compliance
with the servicing and maintenance
requirements of your vehicle war-
ranties.
Detailed warranty information is pro-
vided in your Owner's Handbook &
Warranty Information booklet.
Repairs and adjustments required as
a result of improper maintenance or
a lack of required maintenance are
not covered.
Owner Maintenance
Precautions
Inadequate, incomplete or insuffi-
cient servicing may result in opera-
tional problems with your vehicle that
could lead to vehicle damage, an
accident, or personal injury. This
chapter provides instructions only for
the maintenance items that are easy
to perform. Several procedures can
be done only by an authorized
HYUNDAI dealer with special tools.
Your vehicle should not be modified
in any way. Such modifications may
adversely affect the performance,
safety or durability of your vehicle
and may, in addition, violate condi-
tions of the limited warranties cover-
ing 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.
High voltage caution
Do not disassemble or perform
maintenance on the fuel cell
system unless you are quali-
fied. The fuel cell system can be
highly dangerous since there
are many high voltage parts
inside even if when power is off.
WARNING

7-6
Maintenance
Owner maintenance schedule
When you stop for fuel:
• Check for both fuel cell stack andDevice cooling coolant level in
coolant reservoir.
Check the windshield washer fluid level.
Look for low or under-inflated tires.
While operating your vehicle:
Check for vibrations in the steering wheel. Notice if there is any
increased steering effort or loose-
ness in the steering wheel, or
change in its straight-ahead posi-
tion.
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 reduction gear
occurs, check the reduction gear
fluid level.
Check the reduction gear 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 coolantreservoir.
Check the operation of all exterior lights, including the brake lights,
turn signals and hazard warning
flashers.
Check the inflation pressures of all 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 Fall)
Check radiator, heater and air con-
ditioning hoses for leaks or dam-
age.
Check windshield washer spray and wiper operation. Clean wiper
blades with clean cloth dampened
with washer fluid.
Check headlamp alignment.
Check the seat belts for wear and function.
Be careful when checking the
coolant level when the fuel cell
power module is hot. Scalding
hot coolant and steam may
blow out under pressure. This
could cause burns or other seri-
ous injury.
WARNING

7-13
7
Maintenance
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The high-pressure cooling system
has a reservoir filled with year-round
antifreeze coolant. The reservoir is
filled at the factory.
Check the antifreeze protection and
coolant level at least once a year, at
the beginning of the winter season
and before traveling to a colder cli-
mate.Checking the Coolant Level
Check the condition and connections
of all cooling system hoses and
heater hoses. Replace any swollen
or deteriorated hoses.
The coolant level should be filled
between the MAX and the MIN
marks on the rear side of the coolant
reservoir when the parts in the fuel
cell power module compartment is
cool.
If the coolant level is low, add enough
distilled (deionized) water to bring
the level to the MAX mark, but do not
overfill. If frequent additions are
required, you see an authorized
HYUNDAI dealer for a cooling sys-
tem inspection.
Recommended coolant
When adding coolant, use only
distilled (deionized) water for your
vehicle and never mix hard water in
the coolant filled at the factory.
An improper coolant mixture can result in severe malfunction or
electric devices damage.
Do not use alcohol or methanol coolant or mix them with the spec-
ified coolant.
Do not use a solution that contains more than 60% antifreeze or less
than 35% antifreeze, which would
reduce the effectiveness of the
solution.
OFE078003

7-16
Maintenance
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The high-pressure cooling system
has a reservoir filled with year-round
antifreeze coolant. The reservoir is
filled at the factory.
Check the antifreeze protection and
coolant level at least once a year, at
the beginning of the winter season
and before traveling to a colder cli-
mate.Checking the Coolant Level
Check the condition and connections
of all cooling system hoses and
heater hoses. Replace any swollen
or deteriorated hoses.
When replacing any part of the cool-
ing system there may be loss of
coolant. In that case, fill with an
exclusive coolant for the fuel cell.
When replacing the ion filter car-
tridge, replace the whole stack
coolant.
The coolant level should be filled
between F (MAX) and L (MIN) marks
on the side of the coolant reservoir
when the fuel cell power module is
cool. If the stack cooling coolant level is
low, add enough exclusive coolant
for fuel cell stack to provide protec-
tion against freezing and corrosion in
the authorized HYUNDAI dealer.
In addition, whenever replacing the
ion filter cartridge, add enough exclu-
sive coolant for fuel cell stack.
OFE078005

Stack cooling coolant
When adding stack coolingcoolant, use only exclusive coolant
for fuel cell stack in authorized
HYUNDAI dealer and never mix
any water or liquid.
An improper coolant mixture can result in severe malfunction or
electric devices damage.
If the vehicle is damaged by adding unspecified liquid except exclusive
coolant for fuel cell stack, it will not
be covered by the warranty.
7-17
7
Maintenance
Never remove the
radiator cap or the
drain plug while the
radiator is hot. Hot
coolant and steam
may blow out under pressure,
causing serious injury.
WARNING
OFE078006
Turn the vehicle off and wait
until the parts in the fuel cell
power module compartment
cools down. Use extreme care
when removing the 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.

The electric motor for the cooling fan
is controlled by coolant temperature,
refrigerant pressure and vehicle
speed. As the coolant temperature
decreases, the electric motor will
automatically shut off. This is a nor-
mal condition.
Changing Coolant
For the fuel cell stack, an exclusive
coolant must be used . When chang-
ing the fuel cell stack coolant, we
recommend that coolant be changed
by an authorized HYUNDAI dealer
according to the Maintenance
Schedule at the beginning of this
chapter.To prevent damage to parts in the
fuel cell power module compart-
ment, put a thick towel around the
coolant cap before refilling the
coolant to prevent the coolant
from overflowing into parts in the
fuel cell power module compart-
ment.
NOTICE
7-18
Maintenance
The electric motor for
the cooling fan may
continue to operate
or start up when the
vehicle is not running
and can cause serious injury.
Keep hands, clothing and tools
away from the rotating fan
blades of the cooling fan.
WARNING
Do not use coolant or antifreeze
in the washer fluid reservoir.
Coolant can severely obscure
visibility when sprayed on the
windshield and may cause loss
of vehicle control resulting in an
accident.
Coolant may also cause dam-
age to paint and body trim.
WARNING
Do not mix-up the caps of
device cooling coolant and
stack cooling coolant because
the fluid material is different. If
the cap is mixed, the fuel cell
system may be damage.
We recommend that you con-
sult an authorized HYUNDAI
dealer.
CAUTION

7-29
7
Maintenance
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Tire Care
For proper maintenance, safety, and
maximum fuel economy, you must
always maintain recommended tire
inflation pressures and stay within
the load limits and weight distribution
recommended for your vehicle.

ALWAYS replace tires with the
same size as each tire that
was originally supplied with
this vehicle. Using tires and
wheels other than the recom-
mended sizes could cause
unusual handling characteris-
tics, poor vehicle control, or
negatively affect your vehi-
cle's Anti-Lock Brake System
(ABS) resulting in a serious
accident.
Tire failure may cause loss of
vehicle control resulting in an
accident. To reduce risk of
SERIOUS INJURY or DEATH,
take the following precautions:
Inspect your tires monthly for
proper inflation as well as
wear and damage.
The recommended cold tire
pressure for your vehicle can
be found in this manual and
on the tire label located on the
driver's side center pillar.
Always use a tire pressure
gauge to measure tire pres-
sure. Tires with too much or
too little pressure wear
unevenly causing poor han-
dling.
Replace tires that are worn,
show uneven wear, or are
damaged. Worn tires can
cause loss of braking effec-
tiveness, steering) control, or
traction.
WARNING