check engine LEXUS NX300 2020 Service Manual

3406-3. Do-it-yourself maintenance
LEXUS NX300 Owners Manual_USA_M78389_en
■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.
Check the battery as follows.
■Battery exterior
Make sure that the battery terminals
are not corroded and that there are no
loose connections, cracks, or loose
clamps.
Terminals
Hold-down clamp
WARNING
■When the electric cooling fans are
operating
Do not touch the engine compartment.
With the engine switch in IGNITION
ON mode, the electric cooling fans may
automatically start to run if the air condi-
tioning is on and/or the coolant tempera-
ture is high. Be sure the engine switch is
off when working near the electric cool-
ing fans or radiatorgrille.
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 the battery
A
B

3426-3. Do-it-yourself maintenance
LEXUS NX300 Owners Manual_USA_M78389_en
If none of the washer does not work or
the “Windshield Washer Fluid Low”
appears on the multi-information dis-
play, the washer tank may be empty.
Add washer fluid.
WARNING
●If you accidentally swallow electrolyte
Drink a large quantity of water or milk.
Follow with milk of magnesia, beaten
raw egg or vegetable oil. Get emer-
gency medical attention immediately.
■When there is insufficient battery
fluid
Do not use if there is insufficient fluid in
the battery. There is a possible danger
that the battery may explode.
NOTICE
■When recharging the battery
Never recharge the battery while the
engine is running. Also, be sure all acces-
sories are turned off.
■When adding distilled water
Avoid overfilling. Water spilled during
battery recharging may cause corrosion.
Checking and adding the washer
fluid
WARNING
■When adding washer fluid
Do not add washer fluid when the engine
is hot or operating as washer fluid con-
tains alcohol and may catch fire if spilled
on the engine, etc.
NOTICE
■Do not use any fluid other than
washer fluid
Do not use soapy water or engine anti-
freeze instead of washer fluid.
Doing so may cause streaking on the
vehicle’s painted surfaces, as well as
damaging the pump leading to problems
of the washer fluid not spraying.
■Diluting washer fluid
Dilute washer fluid with water as neces-
sary.
Refer to the freezing temperatures listed
on the label of the washer fluid bottle.

3556-3. Do-it-yourself maintenance
LEXUS NX300 Owners Manual_USA_M78389_en
6
Maintenance and care
1Turn the engine switch off.
2 Open the glove box. Slide off the
damper.
3 Push in the glove box on the vehi-
cle’s outer side to disconnect the
claws. Then pull out the glove box
and disconnect the lower claws. 4
Remove the filter cover.
5 Remove the air conditioning filter
and replace it with a new one.
The “ UP” marks shown on the filter
should be pointing up.
■Checking interval
Inspect and replace the air conditioning fil-
ter according to the maintenance schedule.
In dusty areas or areas with heavy traffic
flow, early replacement may be required.
(For scheduled maintenance information,
please refer to the “Owner’s Manual Sup-
plement” or “Scheduled Maintenance”.)
■If air flow from the vents decreases dra-
matically
The filter may be clogged. Check the filter
and replace if necessary.
■Air conditioning filt er with deodorizing
function
When fragrances are placed in your vehi-
cle, the deodorizing effect may become
significantly weakened in a short period:
When an air conditioning odor comes out
continuously, replace the conditioning filter.
Air conditioning filter
The air conditioning filter must be
changed regularly to maintain air
conditioning efficiency.
Removal method

3586-3. Do-it-yourself maintenance
LEXUS NX300 Owners Manual_USA_M78389_en
1Turn the engine switch off.
2 Open the fuse box cover.
Engine compartment: type A fuse
box
Push the tab in and lift the lid off.
Engine compartment: type B fuse
box
Push the tab in and lift the lid off.
Left side instrument panel
Remove the lid.
3Remove the fuse.
Only type A fuse can be removed using the
pullout tool.
4Check if the fuse is blown.
Replace the blown fuse with a new fuse of
an appropriate amperage rating. The
amperage rating can be found on the fuse
box lid.
Type A
Normal fuse
Blown fuse
Checking and replacing
fuses
If any of the electrical components
do not operate, a fuse may have
blown. If this happens, check and
replace the fuses as necessary.
Checking and replacing fuses
A
B

3626-3. Do-it-yourself maintenance
LEXUS NX300 Owners Manual_USA_M78389_en
■Bulbs that need to be replaced by
the Lexus dealer
 Headlights
 Front turn signal lights (LED type)
 Parking lights and Daytime running
lights
 Front fog lights
 Cornering lights (if equipped)
 Front side marker lights (LED type)
 Side turn signal lights
 Stop/tail lights
 Rear side marker lights
 Back-up light
 Rear turn signal light
 High mounted stoplight
 License plate lights
 Outer foot lights
■LED lights
The lights other than the front side marker
lights (bulb type) and front turn signal lights
(bulb type) each consist of a number of
LEDs. If any of the LEDs burn out, take your
vehicle to your Lexus dealer to have the
light replaced.
■Condensation build-up on the inside of
the lens
Temporary condensation build-up on the
inside of the headlight lens does not indi-
cate a malfunction. Contact your Lexus
dealer for more information in the following
situations:
●Large drops of water ha ve built up on the
inside of the lens.
●Water has built up inside the headlight.
■When replacing light bulbs
 P.359
Before replacing, check the wattage of
the light bulb to be replaced. ( P.415)
■Front side marker lights (bulb type)
1 Turn the bulb base counterclock-
wise.
2 Remove the light bulb.
3 When installing, reverse the steps
listed.
■Front turn signal lights (bulb type)
1 Open the hood and remove the
cover for engine compartment
cover. ( P.333, 336)
2 Remove the cover.
Push the center of the clip and remove
Replacing light bulbs
A

3646-3. Do-it-yourself maintenance
LEXUS NX300 Owners Manual_USA_M78389_en
WARNING
■Replacing light bulbs
●Be sure to stop the engine and turn off
the lights. Do not attempt to replace
the bulb immediately after turning off
the lights.
The bulbs become very hot and may
cause burns.
●Do not touch the glass portion of the
light bulb with bare hands. When it is
unavoidable to hold the glass portion,
use and hold with a clean dry cloth to
avoid getting moisture and oils on the
bulb.
Also, if the bulb is scratched or
dropped, it may blow out or crack.
●Fully install light bulbs and any parts
used to secure them. Failure to do so
may result in heat damage, fire, or
water entering the headlight unit. This
may damage the headlights or cause
condensation to build up on the lens.
●Do not attempt to repair or disassem-
ble light bulbs, connectors, electric cir-
cuits or component parts.
Doing so may result in death or serious
injury due to electric shock.
■To prevent damage or fire
●Make sure bulbs are fully seated and
locked.
●Check the wattage of the bulb before
installing to prev ent heat damage.

3827-2. Steps to take in an emergency
LEXUS NX300 Owners Manual_USA_M78389_en
The light will go off after several driving
trips.
If the light does not go off even after several
trips, contact your Lexus dealer as soon as
possible.
■When the tire pressure warning light
comes on
Inspect the appearance of the tire to check
that the tire is not punctured.
If the tire is punctured: P.387
If the tire is not punctured:
Carry out the following procedure after the
tire temperature has lowered sufficiently.
●Check the tire inflation pressure and
adjust to the appropriate level.
●If the warning light does not go out even
after several minutes, check that the tire
inflation pressure is at the specified level
and carry out initialization. ( P.349)
The warning light may come on again if the
above operations are conducted without
first allowing the tire temperature to lower
sufficiently.
■The tire pressure warning light may
come on due to natural causes
The tire pressure warning light may come
on due to natural causes such as natural air
leaks and tire inflation pressure changes
caused by temperature. In this case, adjust-
ing the tire inflation pressure will turn off the
warning light (after a few minutes).
■When a tire is replaced with a spare tire
The compact spare tire is not equipped with
a tire pressure warning valve and transmit-
ter. If a tire goes flat, the tire pressure warn-
ing light will not turn off even though the flat
tire has been replaced with the spare tire.
Replace the spare tire with the repaired tire
and adjust the tire inflation pressure. The
tire pressure warning lig ht will go off after a
few minutes.
■Conditions that the tire pressure warn-
ing system may not function properly
 P.345
■If the tire pressure warning light fre-
quently comes on after blinking for 1
minute
If the tire pressure wa rning light frequently comes on after blinking
for 1 minute when
the engine switch is turned to IGNITION
ON mode, have it checked by your Lexus
dealer.
■Warning buzzer
In some cases, the buzzer may not be heard
due to being in a noisy location or audio
sound.
WARNING
■If both the ABS and the brake system
warning lights remain on
Stop your vehicle in a safe place immedi-
ately and contact your Lexus dealer. The
vehicle will become extremely unstable
during braking, and the ABS system may
fail, which could cause an accident
resulting in death or serious injury.
■When the electric power steering
system warning light comes on
When the light comes on yellow, the
assist to the power st eering is restricted.
When the light comes on red, the assist
to the power steering is lost and handling
operations of the steering wheel become
extremely heavy. When steering wheel
operations are heavier than usual, grip
the steering wheel firmly and operate it
using more force than usual.
■If the tire pressure warning light
comes on
Be sure to observe the following precau-
tions. Failure to do so could cause a loss
of vehicle control and result in death or
serious injury.
●Stop your vehicle in a safe place as
soon as possible. Adjust the tire infla-
tion pressure immediately.
WARNING
●If the tire pressure warning light comes
on even after tire inflation pressure
adjustment, it is prob able that you have
a flat tire. Check the tire s. If a tire is flat,
change it with the spare tire and have
the flat tire repaired by the nearest
Lexus dealer.

3867-2. Steps to take in an emergency
LEXUS NX300 Owners Manual_USA_M78389_en
speed range
■If “Radar Cruise Control Unavailable
See Owner’s Manual” is shown
The dynamic radar cruise control with full-
speed range system is suspended tempo-
rarily or until the problem shown in the mes-
sage is resolved. (causes and coping
methods: P.197)
■If “Radar Cruise Control Unavailable” is
shown
The dynamic radar cruise control with full-
speed range system cannot be used tempo-
rarily. Use the system when it becomes
available again.
■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 the engine oil, the oil
change system shou ld be reset. (P.337)
■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 deal er. After changing the
engine oil, the oil change system should be
reset. ( P.337)
■If “See Owner’s Manual” is shown
●If the following messages are shown, fol-
lowing the instructions, accordingly.
• “Engine Coolant Temp High” ( P.403)
●If the following messages are shown,
there may be a malfunction.
Immediately have the vehicle inspected
by your Lexus dealer.
• “Braking Power Low”
• “Smart Access System Malfunction”
●If the following messages are shown,
there may be a malfunction.
Immediately stop the vehicle in a safe
place and contact your Lexus dealer.
Continuing to drive the vehicle may be
dangerous.
• “Oil Pressure Low” • “Charging System Malfunction”
• “Transmission Fluid Temp High”
■Warning buzzer
 P.382
NOTICE
■“High Power Consumption Partial
Limit On AC/Heater Operation” is
frequently shown
There is a possible malfunction relating
to the charging system or the battery
may be deteriorating. Have the vehicle
inspected by your Lexus dealer.

3937-2. Steps to take in an emergency
LEXUS NX300 Owners Manual_USA_M78389_en
7
When trouble arises
4Lower the vehicle.
5
Firmly tighten each wheel nut two
or three times in the order shown in
the illustration.
Tightening torque:
76 ft· lbf (103 N· m, 10.5 kgf· m)
6Stow the flat tire, tire jack and all
tools.
■The compact spare tire
●The compact spare tire is identified by the
label “TEMPORARY USE ONLY” on
the tire sidewall.
Use the compact spare tire temporarily,
and only in an emergency.
●Make sure to check the tire inflation pres-
sure of the compact spare tire. ( P.413)
■After completing the tire change
The tire pressure warning system must be
reset. ( P.349)
■When using the compact spare tire
As the compact spare tire is not equipped
with a tire pressure warning valve and trans-
mitter, low inflation pressure of the spare
tire will not be indicated by the tire pressure warning system. Also, if you replace the
compact spare tire afte
r the tire pressure
warning light comes on, the light remains
on.
■When the compact spare tire is
equipped
The vehicle becomes lower when driving
with the compact spare tire compared to
when driving with standard tires.
■If you have a flat front tire on a road cov-
ered with snow or ice
Install the compact spare tire on one of the
rear wheels of the vehicle. Perform the fol-
lowing steps and fit tire chains to the front
tires:
1
Replace a rear tire with the compact
spare tire.
2
Replace the flat front tire with the tire
removed from the rear of the vehicle.
3
Fit tire chains to the front tires.
WARNING
■When using the compact spare tire
●Remember that the sp are tire provided
is specifically designed for use with
your vehicle. Do not use your spare
tire on another vehicle.
●Do not use more than one spare tire
simultaneously.
●Replace the spare tire with a standard
tire as soon as possible.
●Avoid sudden acceleration, abrupt
steering, sudden br aking and shifting
operations that cause sudden engine
braking.

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