2020 LEXUS NX300h engine overheat

4167-2. Steps to take in an emergency
LEXUS NX300h Owners Manual_USA_M78530_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
WARNING
●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 ve hicle in an emer-
gency. It cannot be used to jump start
another vehicle.
If your vehicle overheats
The following may indicate that
your vehicle is overheating.
 The needle of the engine coolant
temperature gauge ( P.84)
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

4187-2. Steps to take in an emergency
LEXUS NX300h Owners Manual_USA_M78530_en
■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 (radiator) for any leaks.
Radiator
Cooling fans
If a large amount of coolant leaks, immedi-
ately contact your Lexus dealer.
4The 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
coolant is unavailable.
6After 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.
A
B
A
B
C
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.

LEXUS NX300h Owners Manual_USA_M78530_en
Alphabetical Index473
Emergency flashers .................................... 378
Emergency, in case ofIf a warning buzzer sounds ..................386
If a warning light turns on ......................386
If a warning message is displayed.....396
If the 12-volt battery is discharged ...... 412
If the electronic key does not operate properly........................................................ 410
If the fuel filler door cannot be opened .........................................................................409
If the hybrid system will not start ........ 407
If the vehicle is trapped in rising water ......................................................................... 379
If you have a flat tire ................................. 400
If you lose your keys.................................409
If you think something is wrong .........384
If your vehicle becomes stuck...............419
If your vehicle has to be stopped in an
emergency ................................................ 378
If your vehicle needs to be towed ...... 381
If your vehicle overheats ..........................416
Energy monitor ............................................... 99
Engine Accessory mode ......................................... 176
Compartment ............................................. 346
Engine switch................................................. 174
Hood................................................................ 344
How to start the hybrid system ............ 174
Identification number ............................... 423
If your vehicle has to be stopped in an
emergency ................................................ 378
Ignition switch (power switch) .............. 174
Overheating...................................................416
Power switch ................................................. 174 Engine compartment cover .................... 347
Engine coolant
Capacity .........................................................425
Checking .......................................................349
Preparing and checking before winter.......................................................................... 277
Warning light ...............................................387
Engine coolant temperature gauge ....... 84
Engine oil Capacity ......................................................... 424
Checking ....................................................... 347
Warning light ...............................................387
Engine switch .................................................. 174
EPS (Electronic Power Steering) Function .......................................................... 270
Warning light .............................................. 388
EV drive mode................................................ 177
EV indicator ...................................................... 68
Event data recorder (E DR) ........................... 8
F
Flat tire .............................................................400
Tire pressure warning system .............357
Floor mats .......................................................... 24
Fluid Brake ................................................................ 427
Transmission................................................. 426
Washer ............................................................ 351
Fog lights Replacing light bulbs ................................ 374
Switch................................................................ 195
Front passenger occupant classification system ................................................................ 41

LEXUS NX300h Owners Manual_USA_M78530_en
Alphabetical Index475
Hybrid battery (traction battery)Location............................................................. 70
Specification ................................................. 424
Hybrid battery air vent ..................................72
Hybrid system ...................................................67 Emergency shut off system ......................73
Energy monitor/consumption screen99
EV drive mode ............................................. 177
High voltage components ....................... 70
Hybrid System Indicator ........................... 87
Hybrid system precautions ..................... 70
Hybrid vehicle driving tips .................... 275
If the hybrid system will not start ........ 407
Overheating...................................................416
Power switch ................................................. 174
Regenerative braking ................................. 68
Starting the hybrid system....................... 174
Vehicle proximity notification system 69
Hybrid System Indicator.............................. 87
Hybrid transmission...................................... 179
I
I/M test ............................................................ 340
Identification Engine ............................................................. 423
Vehicle ............................................................ 422
Ignition switch (Power switch) ................. 174
Illuminated entry system ...........................300
Immobilizer system .........................................75
Indicators ........................................................... 82
Initialization Items to initialize ......................................... 452
Inside rear view mirror ................................144
Instrument panel light control ................... 88
Interior lights..................................................300 Intuitive parking assist
Function .......................................................... 247
Warning message .....................................248
J
JackPositioning a floor jack ............................ 344
Vehicle-equipped jack .......................... 400
Jack handle ....................................................400
Jam protection function Moon roof ........................................................ 151
Power back door closer ........................... 121
Power windows ........................................... 148
Rear seats ........................................................137
K
Keyless entrySmart access system with push-button start ..................................................................126
Wireless remote control ......................... 107
Keys.................................................................... 106 Battery-saving function............................. 127
Electronic key ............................................... 106
Engine switch .................................................174
If the electronic key does not operate properly ........................................................ 410
If you lose your keys ................................ 409
Key number plate ....................................... 106
Keyless entry .........................................110, 126
Mechanical key ............................................ 106
Power switch..................................................174
Replacing the battery .............................. 368
Warning buzzer ........................................... 127
Wireless remote control key ................ 107
Knee airbags .................................................... 32

LEXUS NX300h Owners Manual_USA_M78530_en
Alphabetical Index477
MirrorsInside rear view mirror.............................. 144
Outside rear view mirror defoggers290
Outside rear view mirrors ......................146
Vanity mirrors............................................... 310
Moon roof Jam protection function............................. 151
Operation....................................................... 150
Warning message.......................... 152, 396
Multi-information display Clock .................................................................. 84
Drive information .......................................... 90
Dynamic radar cruise control with full-speed range .............................................. 236
Energy monitor.............................................. 99
Language....................................................... 444
LDA (Lane Departure Alert with steering control) ........................................................ 226
LTA (Lane Tracing Assist)...................... 217
Warning messages ..................................396
N
Noise from under vehicle ...............................6
O
Odometer ......................................................... 84
Oil Engine oil ....................................................... 424
Rear differential oil .................................... 427
Opener Back door..........................................................117
Fuel filler door.............................................. 202
Hood................................................................ 344 Outside rear view mirrors .........................146
Adjusting and folding................................ 146
Blind Spot Monitor (BSM)......................261
Linked mirror functi on when reversing
............................................................................147
Mirror position memory .......................... 138
Outside rear view mirror defoggers290
Outside temperature display .................... 84
Overheating ....................................................416
P
Paddle shift switches ..................................... 181
Panic mode ..................................................... 108
Parking brake Operation ....................................................... 183
Parking brake engaged warning buzzer/message ....................................................... 184
Warning light .............................................. 390
Parking lights Light switch .................................................... 189
Replacing light bulb .................................. 374
Parking Support Brake fu nction (for static
objects) ......................................................... 252 Indicator................................................... 80, 82
Warning light .............................................. 390
Warning messages.................................. 258
PCS (Pre-Collision System) Function ........................................................... 210
PCS switch...................................................... 212
Warning light .............................................. 389
Warning message .................................... 396
Personal lights...............................................300 Switch................................................................ 301
PKSA (Parking Support Alert) .............. 246