2020 LEXUS NX300 key battery

3566-3. Do-it-yourself maintenance
LEXUS NX300 Owners Manual_USA_M78389_en
■When the card key battery needs to be
replaced (if equipped)
The battery for the card key is available only
at Lexus dealers. Your Lexus dealer can
replace the battery for you.
■If the electronic key battery is depleted
The following symptoms may occur:
●The smart access system with push-but-
ton start and wireless remote control will
not function properly.
●The operational range will be reduced.
Prepare the following before replacing
the battery:
 Flathead screwdriver
 Lithium battery CR2032
■Use a CR2032 lithium battery
●Batteries can be purchased at your Lexus
dealer, local electrical appliance shops or
camera stores.
●Replace only with the same or equivalent
type recommended by the manufacturer.
●Dispose of used batteries according to
the local laws.
NOTICE
■When using the air conditioning sys-
tem
Make sure that a filter is always installed.
Using the air conditioning system without
a filter may cause damage to the system.
Electronic key battery
Replace the battery with a new one
if it is depleted.
Items to prepare

3576-3. Do-it-yourself maintenance
LEXUS NX300 Owners Manual_USA_M78389_en
6
Maintenance and care
1Take out the mechanical key.
2
Remove the cover.
To prevent damage to the key, cover the tip
of the flathead screwdriver with a tape.
3Remove the depleted battery.
Insert a new battery with the “+” terminal
facing up.
Replacing the batteryWARNING
■Removed battery and other parts
These parts are small and if swallowed by
a child, they can cause choking. Keep
away from children. Failure to do so
could result in death or serious injury.
NOTICE
■For normal operation after replacing
the battery
Observe the following precautions to
prevent accidents:
●Always work with dry hands.
Moisture may cause the battery to
rust.
●Do not touch or move any other com-
ponent inside the remote control.
●Do not bend either of the battery ter-
minals.

365
LEXUS NX300 Owners Manual_USA_M78389_en
7
7
When trouble arises
When trouble arises
7-1. Essential information
Emergency flashers.................. 366
If your vehicle has to be stopped in an emergency .......................... 366
If the vehicle is trapped in rising water............................................ 367
7-2. Steps to take in an emergency If your vehicle needs to be towed........................................................ 369
If you think something is wrong ........................................................ 373
Fuel pump shut off system ..... 374
If a warning light turns on or a warning buzzer sounds ....... 375
If a warning message is displayed ........................................................ 384
If you have a flat tire.................. 387
If the engine wi ll not start .......395
If you lose your keys ................. 396
If the fuel filler door cannot be opened........................................ 397
If the electronic key does not operate properly .................... 397
If the vehicle battery is discharged ........................................................ 400
If your vehicle overheats ........ 403
If the vehicle becomes stuck 406

3957-2. Steps to take in an emergency
LEXUS NX300 Owners Manual_USA_M78389_en
7
When trouble arises
One of the following may be the cause
of the problem:
There may not be sufficient fuel in
the vehicle’s tank.
Refuel the vehicle.
 The engine may be flooded.
Try to restart the engine again fol-
lowing correct starting proce-
dures.( P.165)
 There may be a malfunction in the
engine immobilizer system.
( P.68)
One of the following may be the cause
of the problem:
 The battery terminal connections
may be loose or corroded.
 The battery may be discharged.
( P.400) The engine starting system may be
malfunctioning due to an electrical
problem such as electronic key battery
depletion or a blown fuse. However, an
interim measure is available to start the
engine. (
P.395)
One of the following may be the cause
of the problem:
 One or both of the battery terminals
may be disconnected.
 The battery may be discharged.
( P.400)
 There may be a malfunction in the
steering lock system.
Contact your Lexus dealer if the problem
cannot be repaired, or if repair procedures
are unknown.
When the engine does not start, the
following steps can be used as an
interim measure to start the engine if
the engine switch is functioning nor-
mally.
Do not use this starting procedure
except in cases of emergency.
1 Set the parking brake.
If the engine will not start
If the engine will not start even
though correct starting procedures
are being followed ( P.165), con-
sider each of the following points:
The engine will not start even
though the starter motor oper-
ates normally.
The starter motor turns over
slowly, the interior lights and
headlights are dim, or the horn
does not sound or sounds at a low
volume.
The starter motor does not turn
over
The starter motor does not turn
over, the interior lights and head-
lights do not turn on, or the horn
does not sound.
Starting the engine in an emer-
gency

3977-2. Steps to take in an emergency
LEXUS NX300 Owners Manual_USA_M78389_en
7
When trouble arises
1Remove the cover inside the lug-
gage compartment by inserting a
screwdriver.
When removing the cover, to pre-
vent damage, cover the tip of the
screwdriver with a rag.
2
After removing the cover, pull the
lever to unlock the fuel filler door
and it will be ready to open as usual.
■Things to check before taking measures
●Make sure that the smart access system
with push-button start has not been deac-
tivated in the customizat ion setting. If it is
off, turn the function on.
●Check if battery-saving mode is set. If it is
set, cancel the function. ( P.117)
Use the mechanical key ( P.98) to
perform the following operations.
If the fuel filler door cannot
b
e opened
If the fuel filler door opener switch
cannot be operated, the following
procedure can be used to open the
fuel filler door.
Opening the fuel filler door
If the electronic key does not
o
perate properly
If communication between the
electronic key and vehicle is inter-
rupted ( P.118) or the electronic
key cannot be used because the
battery is depleted, the smart
access system with push-button
start and wireless remote control
cannot be used. In such cases, the
doors can be opened and the
engine can be started by following
the procedure below.
NOTICE
■In case of a smart access system with
push-button start malfunction or
other key related problems
Take your vehicle with all the electronic
keys provided with your vehicle, includ-
ing the card key, to your Lexus dealer.
Locking and unlocking the doors

3997-2. Steps to take in an emergency
LEXUS NX300 Owners Manual_USA_M78389_en
7
When trouble arises
ACCESSORY mode.
3Firmly depress the brake pedal and
check that message shown on the
multi-information display.
4 Press the engine switch.
In the event that the engine still cannot be
operated, contact your Lexus dealer.
■Stopping the engine
Set the parking brake, shift the shift lever to
P and press the engine switch as you nor-
mally do when stopping the engine.
■Electronic key battery
As the above procedure is a temporary
measure, it is recomme nded that the elec-
tronic key battery be replaced immediately
when the battery is depleted.
■Alarm
Using the mechanical key to lock the doors
will not set the alarm system. If a door is
unlocked using the mechanical key when
the alarm system is set, the alarm may be
triggered.
■Changing engine switch modes
Release the brake pedal and press the engine switch in step
3 above.
The engine does not start and modes will be
changed each time the switch is pressed.
(  P.166)

4007-2. Steps to take in an emergency
LEXUS NX300 Owners Manual_USA_M78389_en
If you have a set of jumper (or booster)
cables and a second vehicle with a bat-
tery, you can jump start your vehicle by
following the steps below.
1Confirm that the electronic key is
being carried.
When connecting the jumper (or booster)
cables, depending on the situation, the
alarm may activate and the doors may lock.
( P.71)
2 Open the hood ( P.333)
If the vehicle battery is dis-
charged
The following procedures may be
used to start the engine if the vehi-
cle’s battery is discharged.
You can also call your Lexus dealer
or a qualified repair shop.
Restarting the engine

4027-2. Steps to take in an emergency
LEXUS NX300 Owners Manual_USA_M78389_en
■Starting the engine when the battery is
discharged
The engine cannot be started by push-start-
ing.
■To prevent battery discharge
●Turn off the headlights and the audio sys-
tem while the engine is off.
●Turn off any unnecessary electrical com-
ponents when the vehicle is running at a
low speed for an extended period, such
as in heavy traffic.
■Charging the battery
The electricity stored in the battery will dis-
charge gradually even when the vehicle is
not in use, due to natural discharge and the
draining effects of certain electrical appli-
ances. If the vehicle is left for a long time,
the battery may discharge, and the engine
may be unable to start. (The battery
recharges automatically during driving.)
■When the battery is removed or dis-
charged
●In some cases, it may not be possible to
unlock the doors using the smart access
system with push-button start when the
battery is discharged. Use the wireless
remote control or the mechanical key to
lock or unlock the doors.
●The engine may not start on the first
attempt after the battery has recharged
but will start normally after the second
attempt. This is not a malfunction.
●The engine switch mode is memorized by
the vehicle. When the battery is recon-
nected, the system will return to the
mode it was in before the battery was dis-
charged. Before di sconnecting the bat-
tery, turn the engine switch off.
If you are unsure what mode the engine
switch was in befo re the battery dis-
charged, be especially careful when
reconnecting the battery.
●Some systems may require initialization.
WARNING
■Avoiding battery fires or explosions
Observe the following precautions to
prevent accidentally igniting the flamma-
ble gas that may be emitted from the bat-
tery:
●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
battery.
■Battery precautions
The battery contains poisonous and cor-
rosive acidic electrol yte, while related
parts contain lead and lead compounds.
Observe the following precautions when
handling the battery:
●When working with the 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 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.