2019 LEXUS NX300H cooling

3176-1. Maintenance and care
LEXUS NX300h Owners Manu-
al_USA_M78287_en
6
Maintenance and care
It may take several minutes before the
warning message disappears.
■Cleaning the air intake vents
●Dust on the air intake vents may inter-
feres cooling of the hybrid battery (trac-
tion battery) and results in poor fuel
consumption. Clean the air intake vents
periodically.
●If continuing to drive the vehicle with
“Maintenance required for Traction bat-
tery cooling parts See owner’s manual”
shown on the multi-information display,
the hybrid battery (traction battery) input
and output may be restricted, leading to a
reduction in hybrid battery (traction bat-
tery) output and a malfunction. It may
cause poor fuel consumption or a mal-
function. If the warning message is shown,
contact your Lexus dealer or clean the air
intake vents immediately.
●If the warning message on the multi-infor-
mation display does not disappear after
cleaning the air intake vents, have the
vehicle inspected by your Lexus dealer.
●Timing of cleaning air intake vents differs
depending on the use environment of the
vehicle.
 Remove dirt and dust using a vac-
uum cleaner.
 Wipe off any excess dirt and dust
with a soft cloth dampened with
diluted detergent.
Use a diluted water solution of approxi-
mately 5% neutral wool detergent.
Wring out any excess water from
the cloth and thoroughly wipe off all
remaining traces of detergent.
 Wipe the surface with a dry, soft
cloth to remove any remaining
moisture. Allow the leather to dry in
a shaded and ventilated area.
■Caring for leather areas
Lexus recommends cleani ng the interior of
the vehicle at least twice a year to maintain
the quality of the vehicle’s interior.
 Remove dirt and dust using a vac-
uum cleaner.
 Wipe it off with a soft cloth damp-
ened with neutral detergent diluted
NOTICE
■When cleaning the air intake vents
When cleaning the air intake vent, make
sure to only use a vacuum to suck out
dust and clogs. If a compressed air blow
gun, etc. is used to blow out dust and
clogs, the dust or clogs may be pushed
into the air intake ve nt, which may affect
the performance of the hybrid battery
(traction battery) and cause a malfunc-
tion.
■To prevent damage to the vehicle
Observe the following precautions. Fail-
ure to do so may cause damage to the
vehicle.
●Do not use water or other liquid to
clean the air intake vents
●Do not install anything but the filters
exclusive for this vehicle to the air
intake vents or use the vehicle without
installing the filters.
Cleaning the leather areas
Cleaning the synthetic leather
areas

3256-3. Do-it-yourself maintenance
LEXUS NX300h Owners Manu-
al_USA_M78287_en
6
Maintenance and care
Tire inflation
pressure
(  P.345)• Tire pressure gauge
• Compressed air source
Washer fluid
( P.333)
• Water or washer fluid
containing antifreeze
(for winter use)
• Funnel (used only for adding water or washer
fluid)
WARNING
The engine compartment contains many
mechanisms and fluids that may move
suddenly, become hot, or become elec-
trically energized. To avoid death or seri-
ous injury, observe the following
precautions.
■When working on the engine com-
partment
●Make sure that the “IGNITION ON”
on the multi-information display and
the “READY” indicator are both off.
●Keep hands, clothi ng and tools away
from the moving fan and engine drive
belt.
●Be careful not to touch the engine,
power control unit, radiator, exhaust
manifold, etc. right after driving as they
may be hot. Oil and other fluids may
also be hot.
●Do not leave anything that may burn
easily, such as paper and rags, in the
engine compartment.
●Do not smoke, cause sparks or expose
an open flame to fuel. Fuel fumes are
flammable.
ItemsParts and tools■When working near the electric cool-
ing fans or radiator grille
Be sure the power switch is off.
With power switch in ON mode, the
electric cooling fans may automatically
start to run if the air conditioning is on
and/or the coolant temperature is high.
(  P.332)
■Safety glasses
Wear safety glasses to prevent flying or
falling material, fluid spray, etc. from get-
ting in your eyes.
NOTICE
■If you remove the air cleaner filter
Driving with the air cleaner filter
removed may cause excessive engine
wear due to dirt in the air.

3286-3. Do-it-yourself maintenance
LEXUS NX300h Owners Manu-
al_USA_M78287_en
Fuse box (P.351)
Engine coolant reservoir ( P.331)
Engine oil filler cap ( P.330)
Power control unit coolant reservoir ( P.332)
Brake fluid reservoir ( P.333)
Radiator ( P.332)
Condenser ( P.332)
Electric cooling fans
Engine oil level dipstick ( P.329)
Washer fluid tank ( P.333)
■12-volt battery
 P.334
Engine compartment
Components
A
B
C
D
E
F
G
H
I
J

3326-3. Do-it-yourself maintenance
LEXUS NX300h Owners Manu-
al_USA_M78287_en
■Power control unit coolant reser-
voirReservoir cap
“FULL” line
“LOW” line
If the level is on or below the “LOW” line,
add coolant up to the “FULL” line.
■Coolant selection
Only use “Toyota Super Long Life Coolant”
or a similar high quality ethylene glycol
based non-silicate, non-amine, non-nitrite,
and non-borate coolant with long-life
hybrid organic acid technology.
U.S.A.:
“Toyota Super Long Life Coolant” is a mix-
ture of 50% coolant and 50% deionized
water.
(Minimum temperature: -31°F [-35°C])
Canada:
“Toyota Super Long Life Coolant” is a mix-
ture of 55% coolant and 45% deionized
water.
(Minimum temperature: -44°F [-42°C])
For more details about coolant, contact
your Lexus dealer.
■If the coolant level drops within a short
time of replenishing
Visually check the radiator, hoses, engine/
power control unit coolant reservoir caps,
drain cock and water pump.
If you cannot find a leak, have your Lexus
dealer test the cap and check for leaks in
the cooling system.
Check the radiator and condenser and
clear away any foreign objects.
If either of the above parts is extremely
dirty or you are not sure of their condi-
tion, have your vehicle inspected by
your Lexus dealer.
A
B
C
WARNING
■When the hybrid system is hot
Do not remove the en gine/power control
unit coolant reservoir caps.
The cooling system may be under pres-
sure and may spray hot coolant if the cap
is removed, causing serious injuries, such
as burns.
NOTICE
■When adding coolant
Coolant is neithe r plain water nor
straight antifreeze. The correct mixture
of water and antifreeze must be used to
provide proper lubrication, corrosion
protection and cooling. Be sure to read
the antifreeze or coolant label.
■If you spill coolant
Be sure to wash it off with water to pre-
vent it from damaging parts or paint.
Checking the radiator and con-
denser
WARNING
■When the hybrid system is hot
Do not touch the radiator or condenser
as they may be hot and cause serious
injuries, such as burns.

3336-3. Do-it-yourself maintenance
LEXUS NX300h Owners Manu-
al_USA_M78287_en
6
Maintenance and care
■Checking fluid level
The brake fluid level should be
between the “MAX” and “MIN” lines
on the tank.
■Adding fluid
Make sure to check the fluid type and
prepare the necessary item.
 Fluid type
FMVSS No.116 DOT 3 or SAE J1703;
FMVSS No.116 DOT 4 or SAE J1704
brake fluid
Items
Clean funnel
■Brake fluid can absorb moisture from
the air
Excess moisture in the brake fluid can cause a dangerous loss of braking efficiency. Use
only newly opened brake fluid.
If none of the washer do not work or
the “Windshield Washer Fluid Low” on
the multi-information display, the
washer tank may be empty. Add
washer fluid.
WARNING
■When the electric cooling fans are
operating
Do not touch the engine compartment.
With the power switch in ON mode, the
electric cooling fans may automatically
start to run if the air conditioning is on
and/or the coolant temperature is high.
Be sure the power switch is off when
working near the electric cooling fans or
radiator grille.
Checking and adding the brake
fluid
WARNING
■When filling the reservoir
Take care as brake fluid can harm your
hands and eyes and damage painted sur-
faces.
If fluid gets on your hands or in your eyes,
flush the affected area with clean water
immediately.
If you still experience discomfort, see a
doctor.
NOTICE
■If the fluid level is low or high
It is normal for the brake fluid level to go
down slightly as the brake pads wear out
or when the fluid leve l in the accumulator
is high.
If the reservoir need s frequent refilling,
there may be a serious problem.
Checking and adding the washer
fluid

3787-2. Steps to take in an emergency
LEXUS NX300h Owners Manu-
al_USA_M78287_en
■If “Traction Battery Needs to be Pro-
tected Refrain From the Use of N Posi-
tion” is shown
This message may be displayed when the
shift lever is in N.
As the hybrid battery (traction battery) can-
not be charged when the shift lever is in N,
when the vehicle is to be stopped for a long
period of time, shift the shift lever to P.
■If “Traction battery needs to be pro-
tected. Shift into P to restart.” is shown
Message is displayed when the remaining
charge for the hybrid battery (traction bat-
tery) is low, because vehicle has been
shifted N for a long period of time.
When operating the vehicle, restart the
hybrid system.
■If “Shift to P Before Exiting Vehicle” is
shown
Message is displayed when the driver’s
door is opened with out turning the power
switch to OFF with the shift lever in any
position other than P.
Shift the shift lever to P.
■If “Shift Is in N Release Accelerator
Before Shifting” is shown
Message is displayed when the accelerator
pedal has been depressed and the shift
lever is in N. Release the accelerator pedal
and shift the shift lever to D, S or R.
■If “Depress Brake When Vehicle Is
Stopped Hybrid Syst em May Overheat”
is shown
Message is displayed when the accelerator
pedal is depressed to maintain the vehicle
position when stopped on a upward slope,
etc.
If this continues, th e hybrid system may
overheat.
Release the accelerator pedal and depress
the brake pedal.
■If “Front Camera Unavailable” or “Front
Camera Unavailable Remove Debris
On Windshield” is shown
The following systems may be suspended
until the problem shown in the message is
resolved. ( P.208, 369)
●PCS (Pre-Collision System)
●LDA (Lane Departure Alert with steering
control)
●Dynamic radar cruise control with full-
speed range
●Adaptive High-beam System
●Automatic High Beam
■If “Oil Maintenance Required Soon” is
shown
Indicates that the engine oil is scheduled to
be changed. (The indicator will not work
properly unless the oil maintenance data
has been reset.)
Check the engine oil, and change if neces-
sary. After changing th e engine oil, the oil
change system should be reset. ( P.330)
■If “Oil Maintenance Required” is shown
Indicates that the engine oil should be
changed. (After the engine oil is changed
and the oil maintenance data has been
reset.)
Check and change the en gine oil, and oil fil-
ter by your Lexus dealer. After changing the
engine oil, the oil change system should be
reset. ( P.330)
■If “See Owner’s Manual” is shown
●If the following messages are shown, fol-
lowing the instruct ions, accordingly.
• “Engine Coolant Temp High” ( P.396)
• “Aux Battery Low” ( P.377)
●If the following messages are shown,
there may be a malfunction.
Immediately have the vehicle inspected
by your Lexus dealer.
• “Hybrid System Malfunction”
•“Check Engine”
• “Hybrid Battery System Malfunction”
• “Accelerator System Malfunction”
• “Braking Power Low”
• “Smart Access System Malfunction”
●If “Maintenance required for Traction bat-
tery cooling parts” is shown, the filters
may be clogged, the air intake vents may
be blocked, or there may be a gap in the
duct. Therefore, perform the following
correction procedure.
• If the air intake vents of the hybrid battery (traction battery) are dirty, perform the
procedure on P. 316 to clean them.
• If the warning message is shown when

3957-2. Steps to take in an emergency
LEXUS NX300h Owners Manu-
al_USA_M78287_en
7
When trouble arises
WARNING
■Avoiding 12-volt battery fires or
explosions
Observe the following precautions to
prevent accidentally igniting the flamma-
ble gas that may be emitted from the 12-
volt battery:
●Make sure each jumper cable is con-
nected to the correct terminal and that
it is not unintentiona lly in contact with
any other than the intended terminal.
●Do not allow the other end of the
jumper cable connected to the “+” ter-
minal to come into contact with any
other parts or metal surfaces in the
area, such as brackets or unpainted
metal.
●Do not allow the + and - clamps of the
jumper cables to come into contact
with each other.
●Do not smoke, use matches, cigarette
lighters or allow open flame near the
12-volt battery.
■12-volt Battery precautions
The 12-volt battery contains poisonous
and corrosive acidic electrolyte, while
related parts contain lead and lead com-
pounds. Observe the following precau-
tions when handling the 12-volt battery:
●When working with the 12-volt battery,
always wear safety glasses and take
care not to allow any battery fluids
(acid) to come into contact with skin,
clothing or the vehicle body.
●Do not lean over the 12-volt battery.
●In the event that battery fluid comes
into contact with the skin or eyes,
immediately wash the affected area
with water and seek medical attention.
Place a wet sponge or cloth over the
affected area until medical attention
can be received.
●Always wash your hands after handling
the 12-volt battery support, terminals,
and other batter y-related parts.
●Do not allow children near the 12-volt
battery.
■After recharging the 12-volt battery
Have the 12-volt battery inspected at
your Lexus dealer as soon as possible.
If the 12-volt battery is deteriorating, con-
tinued use may cause the 12-volt battery
to emit a malodorous gas, which may be
detrimental to the health of passengers.
■When exchanging the 12-volt battery
After exchanging, securely attach the
exhaust hose and exhaust hole plug to
the exhaust hole of the exchanged 12-
volt battery. If not properly installed,
gases (hydrogen) may leak into the vehi-
cle interior, and there is the possible dan-
ger of the gas igniting and exploding.
NOTICE
■When handling jumper cables
When connecting the jumper cables,
ensure that they do not become entan-
gled in the cooling fans or belt.
■To prevent damaging the vehicle
The exclusive jump starting terminal is to
be used when charging the 12-volt bat-
tery from another vehicle in an emer-
gency. It cannot be used to jump start
another vehicle.

3967-2. Steps to take in an emergency
LEXUS NX300h Owners Manu-
al_USA_M78287_en
“Engine Coolant Temp High” is
shown on the multi-information dis-
play
1 Stop the vehicle in a safe place and
turn off the air conditioning system,
and then stop the hybrid system.
2 If you see steam:
Carefully lift the hood after the
steam subsides.
If you do not see steam:
Carefully lift the hood.
3 After the hybrid system has cooled
down sufficiently, inspect the hoses and radiator core (radiator) for any
leaks.
Radiator
Cooling fans
If a large amount of coolant leaks, immedi-
ately contact your Lexus dealer.
4
The coolant level is satisfactory if it
is between the “FULL” and “LOW”
lines on the reservoir.
Reservoir
“FULL” line
“LOW” line
5 Add coolant if necessary.
Water can be used in an emergency if
If your vehicle overheats
The following may indicate that
your vehicle is overheating.
The needle of the engine coolant
temperature gauge ( P.79)
enters the red zone, or a loss of
hybrid system power is experi-
enced. (For example, the vehicle
speed does not increase.)
 “Engine Coolant Temp High” or
“Hybrid System Overheated” is
shown on the multi-information
display.
 Steam comes out from under the
hood.
Correction procedures
A
B
A
B
C