check engine LEXUS RX350 2020 Workshop Manual

3716-3. Do-it-yourself maintenance
6
Maintenance and care
Check if the treadwear indicators are
showing on the tires. Also check the
tires for uneven wear, such as excessive
wear on one side of the tread.
Check the spare tire condition and
pressure if not rotated.
New tread
Worn tread
Treadwear indicator
The location of treadwear indicators is
shown by a “TWI” or “ ” mark, etc.,
molded into the sidewall of each tire.
Replace the tires if the treadwear indica-
tors are showing on a tire.
WARNING
■When adding washer fluid
Do not add washer fluid when the engine
is hot or running as washer fluid contains
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.
Tires
Replace or rotate tires in accor-
dance with maintenance schedules
and treadwear.
Checking tires
A
B
C

3916-3. Do-it-yourself maintenance
6
Maintenance and care
1Turn the engine switch off.
2 Open the fuse box cover.
Engine compartment
Push the tab in and lift the lid off.
Driver’s side instrument panel
Remove the lid.
3Remove the fuse with the pullout
tool. Only some fuses can be removed
using the pullout tool.
4 Check if the fuse is blown.
Normal fuse
Blown fuse
Replace the blown fuse with a new fuse of
an appropriate amperage rating. The
amperage rating can be found on the fuse
box lid.
Many types of fuse are used on this vehicle.
This illustration shows a common type of
fuse used on this vehicle.
■After a fuse is replaced
●If the lights do not turn on even after the
fuse has been replaced, a bulb may need
replacement. ( P.394)
●If the replaced fuse blows again, have the
vehicle inspected by your Lexus dealer.
■If there is an overload in a circuit
The fuses are designed to blow, protecting
the wiring harness from damage.
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

4026-3. Do-it-yourself maintenance
WARNING
■To prevent injury
Before performing any light bulb
replacement procedure, be sure to turn
the engine switch off. Failure to do so
may result in burns from hot components
or a part of your bo dy may get caught on
an operating component, possibly caus-
ing serious injury.
■Replacing light bulbs
●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 the light bulbs, connectors, electric
circuits 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.

4207-2. Steps to take in an emergency
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.
■Electric power steering system warning
light (warning buzzer)
When the battery charge becomes insuffi-
cient or the voltage temporarily drops, the
electric power steeri ng system warning
light may come on and the warning buzzer
may sound.
■When the tire pressure warning light
comes on
Inspect the tires to check if a tire is punc-
tured.
If a tire is punctured: P.426
If none of the tires are punctured:
Turn the engine switch off then turn it to
IGNITION ON mode. Check if the tire
pressure warning light comes on or blinks.
If the tire pressure wa rning light blinks for
1 minute then stays on
There may be a malfunction in the tire
pressure warning syst em. Have the vehicle
inspected by your Lexus dealer immedi-
ately.
If the tire pressure warning light comes
on
1 After the temperature of the tires has
lowered sufficiently, check the inflation
pressure of each tire and adjust them to
the specified level.
2 If the warning light does not turn off
even after several minutes have
elapsed, check that the inflation pres-
sure of each tire is at the specified level
and perform initialization. ( P.381)
If the warning light does not turn off several
minutes after the initia lization has been per-
formed, have the vehicle inspected by your
Lexus dealer immediately.
■The tire pressure warning light may
come on due to natural causes
The tire pressure wa rning 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 light will go off after a
few minutes.
■Conditions that the tire pressure warn-
ing system may not function properly
 P.374
■Customization
Some functions can be customized.
(  P.470)
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 br aking, 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.

4257-2. Steps to take in an emergency
7
When trouble arises
■If “Radar Cruise Control Unavailable” is
displayed
The dynamic radar cruise control with
full-speed range system cannot be used
temporarily. Use the system when it
becomes available again.
■If “Front Camera Unavailable” or “Front
Camera Unavailable See Owner's
Manual” is displayed
The following systems may be suspended
until the problem shown in the message is
resolved. ( P.209, 418)
●PCS (Pre-Collision system)
●LTA (Lane Tracing Assist)
●Automatic High Beam
●RSA (Road Sign Assist) (if equipped)
●Dynamic radar cruise control with
full-speed range
■If “Check Fuel Cap” is displayed (if
equipped)
The fuel tank cap is no t properly installed.
Correctly install the fuel tank cap.
■If “Maintenance Required Soon” is dis-
played (U.S.A. only)
Indicates that all maintenance according to
the driven distance on the maintenance
schedule
* should be performed soon.
Comes on approximately 4500 miles
(7200 km) after the message has been
reset. If necessary, perform maintenance.
Please reset the message after the mainte-
nance is performed. ( P.356)
*: Refer to the separa te “Scheduled Main-
tenance” or “Owner’s Manual Supple-
ment” for the maintenance interval
applicable to your vehicle.
■If “Maintenance Required Visit Your
Dealer” is displayed (U.S.A. only)
Indicates that all maintenance is required to
correspond to the driven distance on the
maintenance schedule
*.
Comes on approximately 5000 miles
(8000 km) after the message has been
reset. (The indicator will not work properly
unless the message ha s been reset.) Per- form the necessary maintenance. Please
reset the message after the maintenance is
performed. (
P.356)
*: Refer to the separate “Scheduled Main-
tenance” or “Owner’s Manual Supple-
ment” for the main tenance interval
applicable to your vehicle.
■If “Oil Maintenance Required Soon” is
displayed
Indicates that the engine oil should be
scheduled to be changed.
Check the engine oil an d change it if neces-
sary. After changing th e engine oil, make
sure to reset the message. ( P.367)
■If “Oil Maintenance Required” is dis-
played
Indicates that the engine oil should be
changed.
Check and change the en gine oil, and oil fil-
ter by your Lexus dealer. After changing the
engine oil, make sure to reset the message.
(  P.367)
■If a message that indicates the need for
visiting your Lexus dealer is displayed
The system or part shown on the
multi-information display is malfunctioning.
Have the vehicle inspected by your Lexus
dealer immediately.
■If a message that indicates the need for
referring to Owner’ s Manual is dis-
played
●“Engine Coolant Temp High” is shown on
the multi-information display, follow the
instructions. ( P.447)
●“Transmission Fluid Temp High” is shown
on the multi-informatio n display, the auto-
matic transmission fluid temperature may
be too high. Immediately stop the vehicle
in a safe place, shif t the shift lever to P
with the engine running and wait until the
message is cleared. If the message is not
cleared, contact your Lexus dealer.
●If the following mess age is shown on the
multi-information display, it may indicate
a malfunction. Have the vehicle inspected
by your Lexus dealer immediately.
• “Access System with Elec. Key Malfunc- tion”

4367-2. Steps to take in an emergency
7Confirm it is not loose after tighten-
ing:
1 Push and pull the tire
2 Try rotating
Visually check to ensure tire is not hung on
surrounding parts.
If looseness or misassembly exists, repeat
steps 2 to 7.
8 Repeat step 7, any time the tire is
lowered or disturbed.
9 Stow the 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 emer-
gency.
●Make sure to check the tire inflation pres-
sure of the compact spare tire. ( P.457)
■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 after the tire pressure
warning light comes on, the light remains
on.
■When the compact spare tire is
equipped
When driving with the compact spare tire
installed, the vehicle he ight will be different
than 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 compact spare tire
provided is specific ally designed for
use with your vehicle. Do not use your
compact spare tire on another vehicle.
●Do not use more than one compact
spare tire simultaneously.
●Replace the compact 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.
■When the compact spare tire is
attached
The vehicle speed may not be correctly
detected, and the following systems may
not operate correctly:
• ABS & Brake assist
•VSC
•TRAC
• Trailer Sway Control
•EPS
•VDIM (if equipped)
• Adaptive Variable Suspension System (if equipped)
• Dynamic radar cruise control with full-speed range

4397-2. Steps to take in an emergency
7
When trouble arises
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.439)
One of the following may be the cause
of the problem:
 One or both of the battery terminals
may be disconnected. ( P.369)
 The battery may be discharged.
( P.443)
 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 Turn the engine switch to IGNI-
TION ON mode and check that the parking brake is set. (
P.179,
185)
2 Shift the shift lever to P.
3 Turn the engine switch to ACCES-
SORY mode.
4 Press and hold the engine switch
for about 15 seconds while
depressing the brake pedal firmly.
Even if the engine can be started using
the above steps, the system may be
malfunctioning. Have the vehicle
inspected by your Lexus dealer.
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

4417-2. Steps to take in an emergency
7
When trouble arises
the lever to open the fuel filler door.
When using a screwdriver, make sure to
wrap its tip with tape to protect the cover.
■When the electronic key does not work
properly
●Make sure that the smart access system
with push-button star t has not been dis-
abled at your Lexus dealer. If it has been
disabled, re-enable it.
●Check if battery-saving mo de is set. If it is
set, cancel the function. ( P.114)
■Unlocking the door
Use the mechanical key ( P.95) in
order to perform th e following opera-
tions:
If the electronic key does not
operate properly
If communication between the
electronic key and vehicle is inter-
rupted ( P.114) 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-rela ted problems
Take your vehicle with all the electronic
keys provided with your vehicle to your
Lexus dealer.
Locking and unlocking the doors

4427-2. Steps to take in an emergency
1Insert the mechanical key while
pulling on the driver’s door handle.
2 Unlock the door.
Turning the key rearward unlocks the
driver’s door. Turning the key again unlocks
the other doors.
3Remove the key, return the handle,
and then pull the handle again.
■Locking the door
1 With the door open, push down the
inside lock button.
2 Close the door.
■Key linked functions
1 Closes the windows and the moon
roof
* or panoramic moon roof* (turn
and hold)
2 Opens the windows and the moon
roof
* or panoramic moon roof* (turn
and hold)
These settings must be customized at your
Lexus dealer.
*: If equipped
1 Ensure that the shift lever is in P and
depress the brake pedal.
2 Touch the Lexus emblem side of the
electronic key to the engine switch.
When the electronic key is detected, a
buzzer sounds and the engine switch will
turn to IGNITION ON mode.
WARNING
■When using the mechanical key and
operating the power windows or the
moon roof or panoramic moon roof
Operate the power window or the moon
roof or panoramic moon roof after
checking to make sure that there is no
possibility of any passe nger having any of
their body parts caught in the window or
the moon roof or panoramic moon roof.
Also, do not allow children to operate the
mechanical key. It is possible for children
and other passengers to get caught in
the power window or the moon roof or
panoramic moon roof.
Starting the engine

4437-2. Steps to take in an emergency
7
When trouble arises
When the smart access system with
push-button start is deactivated in custom-
ization setting, the engine switch will turn
to ACCESSORY mode.
3 Firmly depress the brake pedal and
check that is shown on the
multi-information display.
4 Press the engine switch shortly and
firmly.
In the event that the engine still cannot
be started, contact your Lexus dealer.
■Stopping the engine
Shift the shift lever to P, set the parking
brake, and press the engine switch as you
normally do when stopping the engine.
■Replacing the 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. ( P.389)
■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.179)
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.