2018 LEXUS NX300h cooling

3316-3. Do-it-yourself maintenance
LEXUS NX300h Owners Manu-
al_USA_OM78212U 6
Maintenance and care ■
Power control unit coolant reser-
voir
Reservoir cap
“FULL” line
“LOW” lineIf 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.

332 6-3. Do-it-yourself maintenance
LEXUS NX300h Owners Manu-
al_USA_OM78212U ■
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

3757-2. Steps to take in an emergency
LEXUS NX300h Owners Manu-
al_USA_OM78212U 7
When trouble arises The warning lights and warning buzzers op erate as follows depending on the con-
tent of the message. If a message indicates the need for inspection by a dealer, have
the vehicle inspected by your Lexus dealer immediately.
*
: A buzzer sounds the first time a message is shown on the multi-information display.
■
System warning lights
The master warning light does not come on
or flash in the following cases. Instead, a
separate system warning light will come on
along with a message shown on the multi-
information display.
●
Malfunction of the ABS
The ABS warning light comes on.
( → P.367)
●
Malfunction of the charging system
The charging system warning light comes
on. ( → P.365)
■
If “Hybrid System Overheated Reduced
Output Power” is shown
This message may be displayed when driv-
ing under severe operating conditions. (For example, when driving up a long steep hill.)
Handling method: → P.394■
If “Maintenance required for Traction
battery cooling parts at your dealer” is
shown
The filter may be clogge d, or the air intake
vents or ducts may be blocked. Have the
vehicle inspected by your Lexus dealer.
■
If “Aux Battery Low” is shown
●
When the display goes off after several
seconds *
Maintain the hybrid system operation for
more than 15 minutes and charge the 12-
volt battery.
●
When the display does not go off
Start up the hybrid system using the pro-
cedures for “If the 12-volt battery is dis-Messages and warnings System
warning
light Warning buzzer *
Warning
Comes
on ⎯ Sounds Indicates an important situation, such as
when a system related to driving is malfunc-
tioning or that danger may result if the cor-
rection procedure is not performed
⎯ Comes
on
or flashes Sounds Indicates an important situation, such as
when the systems shown on the multi-infor-
mation display may be malfunctioning
Flashes ⎯ Sounds Indicates a situation, such as when damage
to the vehicle or danger may result
Comes
on ⎯ Does not sound Indicates a condition, such as malfunction of
electrical components, their condition, or
indicates the need for maintenance
Flashes ⎯ Does not sound Indicates a situation, such as when an opera-
tion has been performed incorrectly, or indi-
cates how to perform an operation correctly

3937-2. Steps to take in an emergency
LEXUS NX300h Owners Manu-
al_USA_OM78212U 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.

394 7-2. Steps to take in an emergency
LEXUS NX300h Owners Manu-
al_USA_OM78212U 
“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

3957-2. Steps to take in an emergency
LEXUS NX300h Owners Manu-
al_USA_OM78212U 7
When trouble arises coolant is unavailable.
6 Start the hybrid system and turn the
air conditioning system on to check
that the radiator cooling fans oper-
ate and to check for coolant leaks
from the radiator or hoses.The fans operate when the air conditioning
system is turned on immediately after a
cold start. Confirm that the fans are oper-
ating by checking the fan sound and air
flow. If it is difficult to check these, turn the
air conditioning system on and off repeat-
edly.
(The fans may not oper ate in freezing tem-
peratures.)
7 If the fans are not operating:
Stop the hybrid system immediately
and contact your Lexus dealer.
If the fans are operating:
Have the vehicle inspected at the
nearest Lexus dealer.
8 Check if “Engine Coolant Temp
High” is shown on the multi-infor-
mation display.
If the message does not disappear:
Stop the hybrid system and contact
your Lexus dealer.
If the message is not displayed:
Have the vehicle inspected at the
nearest Lexus dealer. 
If “Hybrid System Overheated” is
shown on the multi-information dis-
play
1 Stop the vehicle in a safe place.
2 Stop the hybrid system and care-
fully lift the hood.
3 After the hybrid system has cooled
down, inspect the hoses and radia-
tor core (radiato r) 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. A
B
A
B
C

396 7-2. Steps to take in an emergency
LEXUS NX300h Owners Manu-
al_USA_OM78212U Water can be used in an emergency if
coolant is unavailable.
6 After stopping the hybrid system
and waiting for 5 minutes or more,
start the hybrid system again and
check if “Hybrid System Over-
heated” is shown on the multi-infor-
mation display.If the message does not disappear:
Stop the hybrid system and contact your
Lexus dealer.
If the message is not displayed:
The hybrid system temperature has
dropped and the vehicle may be driven
normally.
However, if the message appears again fre-
quently, contact your Lexus dealer.
WARNING■
To prevent an accident or injury when
inspecting under the hood of your
vehicle
Observe the following precautions.
Failure to do so may result in serious
injury such as burns.
●
If steam is seen coming from under the
hood, do not open the hood until the
steam has subsided. The engine com-
partment may be very hot. ●
After the hybrid system has been
turned off, check that the “READY”
indicator is off. When the hybrid sys-
tem is operating, the gasoline engine
may automatically start, or the cooling
fan may suddenly operate even if the
gasoline engine stops. Do not touch or
approach rotating parts such as the
fan, which may lead to fingers or cloth-
ing (especially a tie, a scarf or a muf-
fler) getting caught, resulting in serious
injury. ●
Do not loosen the coolant reservoir
cap while the hybrid system and radia-
tor are hot.
High temperature steam or coolant
could spray out.
NOTICE■
When adding engine/power control
unit coolant
Add coolant slowly after the hybrid sys-
tem has cooled down sufficiently. Adding
cool coolant to a hot hybrid system too
quickly can cause dama ge to the hybrid
system. ■
To prevent damage to the cooling sys-
tem
Observe the following precautions: ●
Avoid contaminating the coolant with
foreign matter (such as sand or dust
etc.).
●
Do not use any coolant additive.

4038-1. Specifications
LEXUS NX300h Owners Manu-
al_USA_OM78212U 8
Vehicle specifications as an example):
• The 0W in 0W-20 indicates the
characteristic of the oil which allows
cold startability. Oils with a lower
value before the W allow for easier
starting of the engine in cold
weather.
• The 20 in 0W-20 indicates the vis-
cosity characteristic of the oil when
the oil is at high temperature. An oil
with a higher viscosity (one with a
higher value) may be better suited if
the vehicle is operated at high
speeds, or under extreme load con-
ditions. How to read oil container label:
The International Lubricant Specifica-
tion Advisory Committee (ILSAC)
Certification Mark is added to some oil
containers to help you select the oil you
should use.
*
: The coolant capacity is the quantity of reference.
If replacement is necessary, contact your Lexus dealer.Cooling system Capacity *
Gasoline
engine 
Vehicles with towing package
7.7 qt. (7.3 L, 6.4 Imp.qt.) 
Vehicles without towing package
7.1 qt. (6.7 L, 5.9 Imp.qt.)
Power con-
trol unit 3.3 qt. (3.1 L, 2.7 Imp.qt.)
Coolant type Use either of the following:
• “Toyota Super Long Life Coolant”
• Similar high-quality ethy lene glycol-based non-
silicate, non-amine, non-nitrite, and nonborate
coolant with long-life hy brid organic acid tech-
nology
Do not use plain water alone.