2021 LEXUS NX300h engine overheat

4187-2. Steps to take in an emergency
LEXUS NX300h Owners Manual_USA_M78578_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

4207-2. Steps to take in an emergency
LEXUS NX300h Owners Manual_USA_M78578_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.

474Alphabetical Index
LEXUS NX300h Owners Manual_USA_M78578_en
Replacing the battery...............................369
Electronically Controlled Brake System (ECB) .............................................................272
Emergency flashers ....................................380
Emergency, in case of If a warning buzzer sounds ................. 388
If a warning light turns on ..................... 388
If a warning message is displayed.....398
If the 12-volt battery is discharged ...... 414
If the electronic key does not operate properly......................................................... 412
If the fuel filler door cannot be opened .............................................................................411
If the hybrid system will not start ........409
If the vehicle is trapped in rising water .......................................................................... 381
If you have a flat tire .................................. 402
If you lose your keys.....................................411
If you think something is wrong .........386
If your vehicle becomes stuck............... 421
If your vehicle has to be stopped in an
emergency ............................................... 380
If your vehicle needs to be towed .....383
If your vehicle overheats ......................... 418
Energy monitor ............................................... 99
Engine .............................................................. 425 Accessory mode ......................................... 177
Compartment .............................................348
Engine switch................................................. 174
Hood................................................................ 346
How to start the hybrid system ............ 174
Identification number ............................... 425
If your vehicle has to be stopped in an
emergency ............................................... 380
Ignition switch (power switch) .............. 174
Overheating.................................................. 418
Power switch ................................................. 174
Engine compartment cover .................... 349
Engine coolant Capacity ......................................................... 427
Checking .........................................................351
Preparing and checking before winter .......................................................................... 279
Warning light .............................................. 389
Engine coolant temperature gauge ....... 84
Engine oil Capacity ......................................................... 426
Checking .......................................................349
Warning light .............................................. 389
Engine switch .................................................. 174
EPS (Electronic Power Steering) Function .......................................................... 272
Warning light .............................................. 390
EV drive mode................................................178
EV indicator ...................................................... 68
Event data recorder (E DR) ........................... 8
F
Flat tire ............................................................. 402
Tire pressure warning system ............ 359
Floor mats .......................................................... 24
Fluid Brake ................................................................ 429
Transmission.................................................428
Washer ...........................................................353
Fog lights Replacing light bulbs ................................375
Switch................................................................ 196
Front passenger occupant classification system ................................................................ 41
Front passenger’s seat belt reminder light .......................................................................... 393
Front seat heaters........................................300
Front seats ........................................................132 Adjustment ......................................................132
Cleaning .........................................................335
Correct driving posture ............................ 25
Driving position memory ........................ 138
Head restraints............................................... 141
Power easy access system .................... 138
Seat heaters ................................................. 300
Seat position memory .............................. 138
Front side marker lights Light switch .................................................... 190

LEXUS NX300h Owners Manual_USA_M78578_en
Alphabetical Index475
Replacing light bulbs................................ 376
Wattage............................................................ 431
Front turn signal lights Replacing light bulbs.................... 375, 376
Turn signal lever .......................................... 183
Wattage............................................................ 431
Fuel Capacity ......................................................... 425
Fuel gauge ....................................................... 84
Gas station information..........................484
Information .................................................... 432
Refueling ........................................................ 203
Type.................................................................. 425
Warning light ............................................... 393
Fuel filler door ............................................... 203 Refueling ........................................................ 203
When the fuel filler door cannot be opened ............................................................411
Fuses ................................................................... 371
G
Garage door opener ................................. 322
Gas station information ............................ 484
Gauges ............................................................... 84
Glove box ....................................................... 306
Glove box light ............................................. 306
Grocery bag hooks .................................... 309
H
Head restraints ................................................ 141
Head-up display.............................................. 95
Headlights ....................................................... 190 Automatic headlight leveling .................. 191
Automatic High Beam ..............................193
Light switch .................................................... 190
Replacing light bulbs................................ 375
Heated steering wheel ..............................300
Heaters Automatic air conditioning system ..... 291
Heated steering wheel............................ 299
Outside rear view mirrors .................... 292 Seat heaters ................................................. 300
High mounted stoplight Replacing light bulb ..................................375
Hill-start assist control ............................... 273
Hood ................................................................. 346 Open................................................................346
Hooks Cargo hooks............................................... 308
Retaining hooks (floor mat) ..................... 24
Horn ....................................................................144
Hybrid battery (traction battery) Location ............................................................. 70
Specification ................................................. 426
Hybrid battery air vent ..................................72
Hybrid system ...................................................67 Acoustic vehicle alerting system...........69
Emergency shut off system...................... 73
Energy monitor/consumption screen99
EV drive mode............................................. 178
High voltage components ....................... 70
Hybrid System Indicator ........................... 87
Hybrid system precautions...................... 70
Hybrid vehicle driving tips .................... 277
If the hybrid system will not start ....... 409
Overheating .................................................. 418
Power switch..................................................174
Regenerative braking .................................68
Starting the hybrid system .......................174
Warning lights ............................................ 388
Hybrid System Indicator......................84, 87
Hybrid transmission..................................... 180
I
I/M test ............................................................ 342
Identification Engine..............................................................425
Vehicle ............................................................ 424
Ignition switch (Power switch) ................. 174
Illuminated entry system ........................... 302
Immobilizer system........................................ 75
Indicators ........................................................... 82

LEXUS NX300h Owners Manual_USA_M78578_en
Alphabetical Index477
Vanity lights .................................................... 312
Wattage............................................................ 431
Welcome light illumination control ....... 111
Light bulbs Replacing ........................................... 375, 376
Wattage............................................................ 431
LTA (Lane Tracing Assist) .........................218
Luggage cover .............................................. 310
M
Maintenance Do-it-yourself maintenance ................. 344
General maintenance .............................340
Maintenance data...................................... 424
Maintenance requirements .................. 339
Malfunction indicator lamp ..................... 389
Meter Head-up display ........................................... 95
Indicators ..........................................................80
Instrument panel light control ................88
Meters ................................................................ 84
Multi-information display .......................... 89
Warning lights ............................................ 388
Warning messages ..................................398
Micro dust and pollen filter ..................... 297
Mirrors Inside rear view mirror.............................. 144
Outside rear view mirror defoggers 292
Outside rear view mirrors ......................146
Vanity mirrors................................................ 312
Moon roof Jam protection function............................. 151
Operation....................................................... 150
Warning message.......................... 152, 398
Multi-information display Clock .................................................................. 84
Drive information .......................................... 90
Dynamic radar cruise control with full-speed range .............................................. 237
Energy monitor.............................................. 99
Language....................................................... 446
LDA (Lane Departure Alert with steering control) ........................................................ 227
LTA (Lane Tracing Assist) ..................... 218
Warning messages.................................. 398
N
Noise from under vehicle ...............................6
O
Odometer ......................................................... 84
Oil Engine oil........................................................ 426
Rear differential oil......... ..................... ....... 429
Opener Back door ......................................................... 117
Fuel filler door ..............................................203
Hood ................................................................346
Outside rear view mirrors .........................146 Adjusting and folding................................ 146
Blind Spot Monitor (BSM).................... 262
Linked mirror functi on when reversing
............................................................................147
Mirror position memory .......................... 138
Outside rear view mirror defoggers 292
Outside temperature display .................... 84
Overheating ................................................... 418
P
Paddle shift switches ....................................182
Panic mode ..................................................... 108
Parking brake Operation ....................................................... 184
Parking brake engaged warning buzzer/message ....................................................... 185
Warning light ...............................................392
Parking lights Light switch .................................................... 190
Replacing light bulb ..................................375
Parking Support Brake fu nction (for static
objects) ......................................................... 253 Enabled/disabled on the system .......254