Fuel system HYUNDAI NEXO 2021 Owner's Guide

H12
Fuel filler door
Opening the fuel filler door
1. Turn the vehicle off.
2. Push the fuel filler door opener
button. The fuel filler door does not
open if the vehicle is not off.
The fuel filler door may open
after several seconds from turn-
ing off the vehicle. However, in
cold weather, the fuel door may
not open for about 45 seconds
until the cluster message
"Powering down..." disappears.
This is for protecting the fuel
cell system.
3. Pull the fuel filler door (1) out to
fully open.
4. Pull the fuel filler cap (2).
5. Place the cap on the fuel filler door.
NOTICE
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OFEQ018014L
OFEQ018015N

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Information
If the fuel filler door does not open
because ice has formed around it, tap
lightly or push on the door to break
the ice and release the door. Do not
pry on the door. If necessary, spray
around the door with an approved de-
icer fluid (do not use radiator anti-
freeze) or move the vehicle to a warm
place and allow the ice to melt.
Closing the fuel filler door
1. Cover the fuel filler with the cap.
2. Close the fuel filler door until it is
latched securely.i
If the fuel filler cap requires
replacement, use parts for
replacement from an author-
ized Hyundai dealer. An incor-
rect fuel filler cap can result in
a serious malfunction of the
fuel system. Contact an
authorized HYUNDAI dealer
for replacement.
If the fuel filler door is not
completely closed, the vehicle
is not turned on. Close the
fuel filler door and turn on the
vehicle.
WARNING
According to the hydrogen
fueling station condition the
hydrogen may not be filled
fully and the driving distance
may change accordingly. The
hydrogen may not be charged
fully if the fueling station does
not satisfy the fueling method
specified in the fueling. stan-
dard (SAE J2601) or if the
hydrogen is not enough in the
station, the fueling facility
has failure, etc.
Depending on the remaining
hydrogen in the vehicle and
ambient temperature, the time
required for fueling may vary.
More time may be required for
fueling if the remaining hydro-
gen level is low and the
weather is hot. Also, required
time may be longer if the
hydrogen cooling tempera-
ture of the fueling station is
high.
The distance to empty may
vary depending on the driving
environment (weather, traffic,
etc.) and driving method
(rapid acceleration, heating
and air conditioning, etc.).WARNING

H15
Warning and indicator lights
OFE048100N
1. Power gauge
2. Speedometer
3. Fuel cell stack temperature gauge
4. Fuel gauge
5. Odometer/LCD display/Trip computer
6. Warning and indicator lights
Air bag warningCharging system warningElectronic Stability Control
(ESC) OFF indicator Forward Collision-
Avoidance Assist (FCA)
system warning
Seat belt warningLow fuel level warning Immobilizer Indicator
Parking brake &
brake fluid warningLow tire pressure warningTurn Signal IndicatorEPBElectronic Parking Brake
(EPB) warning
Regenerative brake
warningService warning High Beam IndicatorAUTO
HOLDAUTO HOLD Indicator
Anti-lock brake system
(ABS) warningPower down warning Light ON IndicatorMaster Warning
Electronic Brake force
Distribution (EBD) warning
Hydrogen gas leak
warning (Red) Ready indicatorLED Headlamp warning
Hydrogen leak sensor
warning (Yellow)Lane Keeping Assist (LKA)
system indicator
Electric Power Steering
(EPS) warningElectronic Stability Control
(ESC) indicator
Yellow
❈For more details, refer to the ‘Instrument cluster’ in Chapter 3.

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LCD Display Messages
Check FCEV System
This warning message is displayed
and the warning light illuminates
when the FCEV system is not work-
ing properly.
In this case,have the vehicle checked
by an authorized HYUNDAI dealer.
Power limited due to high
coolant temperature
This warning message is displayed
when the FCEV's stack is overheat-
ed and the power supply to the
FCEV system is limited.
If the warning light stays on when in
"Ready ( )" state or while driving
the vehicle, this indicates that the
fuel cell stack may have failure. In
this case, we recommend you to
drive safely and have your vehicle
inspected by an authorized
HYUNDAI dealer.Replace fuel cell coolant and
filter
This warning message is displayed
when the fuel cell coolant and filter
need to be checked.
In this case, have the vehicle
checked by an authorized HYUNDAI
dealer.Refill electric components
coolant
This warning message is displayed
when the electronic device's coolant
level in the tanks is low.
In this case, have the vehicle
checked by an authorized HYUNDAI
dealer and refill the coolant.
Stop vehicle and check power
supply
This warning message is displayed
when any serious malfunction of the
vehicle is detected.
In this case, drive the vehicle imme-
diately to a safe area and turn off the
vehicle. Then turn the vehicle on
again.
If the message is displayed again,
have the vehicle checked by an
authorized HYUNDAI dealer.
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Do not drive on uphill or accel-
erate suddenly when the power
down warning light is on. The
power is limited and may result
in dangerous situation or vehi-
cle damage.
CAUTION

H17
Close fuel door before turning
vehicle On
This warning message is displayed
when you turn on the vehicle with
the fuel filler door open. Close the
fuel filler door and turn on the vehicle
again.
Hydrogen tank overfilled due
to hydrogen station error
This warning message is displayed
when the hydrogen tank is over-refu-
eled with the hydrogen due to a prob-
lem of the fueling station.
Turn off the vehicle and then turn on
the vehicle. If the message is dis-
played again, have the vehicle
checked by an authorized HYUNDAI
dealer.Small hydrogen leak possible
This warning message is displayed
when the minor hydrogen leakage is
detected in the vehicle. In this case,
have the vehicle checked by an
authorized HYUNDAI dealer.
If the vehicle has to be stopped due
to the leakage, hydrogen gas leak
warning light (red) will illuminate and
'Hydrogen leak detected. Stop safely
immediately.' message is displayed.
Power limited due to low
hydrogen tank temperature
This warning message is displayed
to protect the battery and fuel cell
system when the temperature of the
hydrogen tanks is low.
If this message is still displayed after
the ambient temperature has
increased enough, have the vehicle
checked by an authorized HYUNDAI
dealer.Hydrogen tank temperature
out of range! Stop safely
immediately
This warning message is displayed
to protect the hydrogen tank system
when the temperature of the hydro-
gen tank is too high or too low.
Turn off the vehicle and stop to let
the temperature of the hydrogen tank
go down.▲ ▲
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If this message is still displayed
after the vehicle is turned off
and stopped for a sufficient
time, we recommend you to
stop driving and have your vehi-
cle immediately inspected by an
authorized HYUNDAI dealer.
WARNING

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Hydrogen leak detected. Stop
safely immediately
This warning message is displayed
and the hydrogen gas leak warning
light (red) illuminates when the
hydrogen leakage is detected in the
vehicle. In this case, we recommend
you to stop driving and stop the vehi-
cle immediately at a safe area. Then
turn off the vehicle and have your
vehicle inspected by an authorized
HYUNDAI dealer.
Check hydrogen leak sensor
This warning message is displayed
and the light showing the malfunction
of the hydrogen leakage detection
sensor illuminates when there is a
malfunction with the hydrogen leak-
age detection sensor. In this case,
have the vehicle checked by an
authorized HYUNDAI dealer.
Refueling…
This warning message is displayed
while refueling the vehicle. Do not
turn on the vehicle and wait until the
refueling is complete.Check fuel door sensor
This warning message is displayed
when there is a malfunction with the
sensor located below the fueling inlet
which is used for communicating
with the fueling station. Check and
remove if there is any foreign sub-
stance around the fueling inlet.
If this message is still displayed after
the foreign substance is removed,
have the vehicle checked by an
authorized HYUNDAI dealer.
Open fuel door after turning
vehicle Off
This warning message is displayed
when you try to open the fuel filler
door while the vehicle is turned on.
Turn of the vehicle and open the fuel
filler door. If the message is still dis-
played after a while, have the vehicle
checked by an authorized HYUNDAI
dealer.Replace hydrogen tank.
Maximum number of refill
cycles exceeded
This warning message is displayed
when the number of times refueling
the vehicle exceeds the predefined
number (4,995 times). The fuel cell
system stops operation for safety
even if the vehicle is refueled enough
and when there is no problem with
the vehicle. In this case, have the
hydrogen storage system replaced
by an authorized HYUNDAI dealer.
Power limited due to fuel cell
system error
This warning message is displayed
when there is a malfunction with the
fuel cell system and the power sup-
ply to the fuel cell system is limited.
If the warning light stays on when in
"Ready ( )" state or while driving
the vehicle, this indicates that the
fuel cell system may have failure. In
this case, have the vehicle checked
by an authorized HYUNDAI dealer.
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H19
Check fuel cell system! Stop
safely immediately
This warning message is displayed
when any serious malfunction of the
fuel cell system is detected.
In this case, immediately park the
vehicle at a safe area and turn off the
vehicle. Then turn the vehicle on
again.
If the message is displayed again,
have the vehicle checked by an
authorized HYUNDAI dealer.
Unable to start vehicle! Check
high voltage system
This warning message is displayed
when there is a malfunction with the
high voltage system.
If the vehicle will not turn on, have
the vehicle checked by an authorized
HYUNDAI dealer.Unable to start vehicle.
Hydrogen too low
This warning message is displayed
when the fuel is empty and the vehi-
cle is not turned on. The vehicle will
not turn on and we recommend that
you have your vehicle inspected by
an authorized HYUNDAI dealer.
Check FCEV System! Stop and
turn vehicle Off
This warning message is displayed
when there is a temporary malfunc-
tion with the FCEV system. Stop the
vehicle at a safe area and turn off the
vehicle. Then turn on the vehicle
after a while. If the message is dis-
played again, have the vehicle
checked by an authorized HYUNDAI
dealer.Check 12V battery. Stop safely
and engage parking brake
This warning message is displayed
when the voltage of the auxiliary bat-
tery is low. Stop the vehicle at a safe
area and turn off the vehicle. Then
turn on the vehicle after a while. If the
message is displayed again, have
the vehicle checked by an authorized
HYUNDAI dealer.
Low fuel
This warning message is displayed
when you need to refuel the vehicle.
Refuel the vehicle immediately at a
nearby fueling station.
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CategoryQuestionsAnswers
Vehicle
overview
(10 items)
1. Does a Hydrogen Fuel Cell Electric
Vehicle (FCEV) have similar performance
to standard, non-electric vehicles?FCEV performance characteristics are generally equivalent to stan-
dard vehicles, but with better noise control.
2. If water floods the fuel cell power module
compartment, due to heavy rain or flood-
ing for example, will it have any effect on
the vehicle?
Every component housed in the fuel cell power module compart-
ment is designed to be waterproof through evaluation which meets
the IP69K standard, so you don't have to worry about any potential
faults or safety problems if water contacts the fuel cell. However, if
the vehicle is fully flooded, have the vehicle checked by an author-
ized HYUNDAI dealer.
3. When starting or stopping the vehicle,
there's a noise. Is this noise cause for
concern?
The sound you hear is normal. The noise emanates from the blower
motor starting up to remove any residual water vapor in the fuel cell
system.Also, when you turn on the vehicle you may hear a brief oper-
ation sound from the hydrogen storage system which is located on the
back of the vehicle. This is a normal sound which is occurred when the
system tries to balance the pressure between the hydrogen tanks.
4. Is there a possibility that extremely cold
weather can prevent vehicle startup?
In most instances, the vehicle can get startup in cold weather with-
out any problems. However, the vehicle may not start if the vehicle is
parked with the ignition off for over a week in cold temperatures. In
this case, turn on the vehicle 2-3 times repeatedly. If you will not be
turning on the ignition for more than a week in cold weather, it is
recommended that you park the vehicle inside a building, if possible.
Notice)
In particular, make sure to park the vehicle indoor when the temper-
ature is below -30°C. If the vehicle is parked outside for over 12
hours under such weather fuel cell components may be damaged.
Also, avoid driving under such weather to prevent damaging the fuel
cell components.

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CategoryQuestionsAnswers
Vehicle
overview
(10 items)
5. Why is there an engine noise at low
speeds, even though there is no engine?The noise is generated from the air compressor and cooling pump
working to supply air to the fuel cell or it's from Virtual Engine
Sound System (VESS).
6. When turning on and off the vehicle in
cold weather, there's a loud noise. Is this
noise cause for concern?
When you turn on the vehicle or turn off the vehicle in cold weather,
the air compressor removes the generated water inside the fuel cell
system and the noise is generated during this process, which is nor-
mal. In this case, certain amount of water may drain through the
vehicle bottom and exhaust pipe.
7. Why does a noise emanate when the
vehicle moves in reverse?
Normally, the noise is a result of the Virtual Engine Sound System
(VESS) working when the FCEV runs at low velocity (1~12 mph
(1~20 km/h)) after shifting to D or N. However, when shifting to R,
the VESS operates immediately, regardless of vehicle speed. In
addition, a separate warning chime will sound to have the pedestri-
an aware of the approaching vehicle.
8. The FCEV is equipped with a reduction
gear but no transmission. What makes it
different from standard vehicles?
The transmission of standard vehicles delivers power as conditions
require via multiple transmission gears. However, the reduction gear
of the FCEV is designed to deliver power by reducing the motor's
RPM as operating conditions dictate, or to move backwards by
reversing the rotational direction of the shaft.

H32
CategoryQuestionsAnswers
Vehicle
overview
(10 items)
9. Can driving on test roads or over speed
bumps damage the high voltage battery
and hydrogen tank?
The high voltage battery and hydrogen tank are unlikely to be damaged
under normal driving conditions. However, if the system begins to mal-
function due to a direct and serious vehicular impact, you are informed
of those system errors via warning lights on and the LCD display.

10. A water-like liquid is being discharged
from the muffler and bottom of the vehi-
cle. Is it harmful to humans?
Water or vapor discharged is generated from electrochemical reac-
tions in the fuel cell stack, and is not harmful to humans. However,
liquids generated from the reactions can be somewhat acidic, so DO
NOT touch or ingest the liquid!
Also, the water discharged when parking the vehicle indoor may
make a puddle on the floor. Be careful as such puddle can freeze
and result in accident during winter.
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