2020 LEXUS RX450H warning light

5917-3. Do-it-yourself maintenance
7
Maintenance and care
RX350/RX350L_U
*: Vehicles with single-beam headlights
Tire inflation pres-
sure (P. 613)• Tire pressure gauge• Compressed air source
Washer fluid
( P. 603)• Water or washer fluid containing antifreeze (for winter use)
• Funnel (used only for adding water or washer fluid)
WARNING
The engine compartment contains many mechan isms and fluids that may move suddenly,
become hot, or become electrically energize d. To avoid death or serious injury, observe
the following precautions.
■When working on the engine compartment
●Keep hands, clothing and tools away from the moving fan and engine drive belt.
●Be careful not to touch the engine, radiator, exhaust manifold, etc. right after driving
as they may be hot. Oil and other fluids may also be hot.
●Do not leave anything that may burn easily, such as paper and rags, in the engine
compartment.
●Do not smoke, cause sparks or expose an open flame to fuel or the battery. Fuel and
battery fumes are flammable.
●Be extremely cautions when working on the battery. It contains poisonous and corro-
sive sulfuric acid.
■When working near the electric cooling fans or radiator grille
Be sure the engine switch is off.
With the engine switch in IGNITION ON mode, the electric cooling fans may auto-
matically start to run if the air conditioning is on and/or the coolant temperature is high.
(  P. 599)
■Safety glasses
Wear safety glasses to prevent flying or falling material, fluid spray, etc. from getting in
your eyes.
NOTICE
■If you remove the air cleaner filter
Driving with the air cleaner f ilter removed may cause excessive engine wear due to dirt
in the air.
ItemsParts and tools

5927-3. Do-it-yourself maintenance
RX350/RX350L_U
Pull the hood lock release lever.
The hood will pop up slightly.
Pull up the auxiliary catch lever and
lift the hood.
Hood
Release the lock from the inside of the vehicle to open the hood.
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WARNING
■Pre-driving check
Check that the hood is fully closed and locked.
If the hood is not locked properly, it may op en while the vehicle is in motion and cause
an accident, which may result in death or serious injury.

6007-3. Do-it-yourself maintenance
RX350/RX350L_U
■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.
■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.
Brake fluid
Fluid type FMVSS No.116 DOT 3 or SAE J1703 brake fluid
ItemsClean funnel
WARNING
■When filling the reservoir
Take care as brake fluid can harm your hands and eyes and damage painted surfaces.
If fluid gets on your hands or in your ey es, flush the affected area with clean water
immediately.
If you still experience di scomfort, 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 level in the accumulator is high.
If the reservoir needs frequent ref illing, there may be a serious problem.

6027-3. Do-it-yourself maintenance
RX350/RX350L_U
WARNING
■Chemicals in the battery
Battery contains poisonous and corrosive sulfuric acid and may produce hydrogen gas
which is flammable and explosive. To reduce the risk of death or serious injury, take the
following precautions while wor king on or near the battery:
●Do not cause sparks by touching the battery terminals with tools.
●Do not smoke or light a match near the battery.
●Avoid contact with eyes, skin and clothes.
●Never inhale or swallow electrolyte.
●Wear protective safety glasses when working near the battery.
●Keep children away from the battery.
■Where to safely charge the battery
Always charge the battery in an open area . Do not charge the battery in a garage or
closed room where there is insufficient ventilation.
■How to recharge the battery
Only perform a slow charge (5 A or less) . The battery may explode if charged at a
quicker rate.
■Emergency measures regarding electrolyte
●If electrolyte gets in your eyes
Flush your eyes with clean water for at least 15 minutes and get immediate medical
attention. If possible, continue to apply water with a sponge or cloth while traveling to
the nearest medical facility.
●If electrolyte gets on your skin
Wash the affected area thoroughly. If you fe el pain or burning, get medical attention
immediately.
●If electrolyte gets on your clothes
It can soak through clothing on to your s kin. Immediately take off the clothing and fol-
low the procedure above if necessary.
●If you accidentally swallow electrolyte
Drink a large quantity of water or milk. Get emergenc y medical attention immedi-
ately.
■When there is insufficient battery fluid
Do not use if there is insufficient fluid in th e 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 accessories
are turned off.
■When adding distilled water
Avoid overfilling. Water spilled during battery recharging may cause corrosion.

6057-3. Do-it-yourself maintenance
7
Maintenance and care
RX350/RX350L_U
Your vehicle is equipped with a tire pressure warning system that uses tire pres-
sure warning valves and transmitters to detect low tire inflation pressure before
serious problems arise.
◆Installing tire pressure warning valves and transmitters
When replacing tires or wheels, tire pr essure warning valves and transmitters
must also be installed.
When new tire pressure wa rning valves and transmitters are installed, new ID
codes must be registered in the tire pressure warning computer and the tire
pressure warning system must be initia lized. Have tire pressure warning valve
and transmitter ID codes registered by your Lexus dealer. ( P. 606)
◆Initializing the tire pressure warning system
■The tire pressure warning system must be initialized in the following circum-
stances:
●When the tire inflation pressure is changed such as when changing travel-
ing speed.
●When the tire inflation pressure is changed such as when the tire size is
changed.
●When rotating the tires
When the tire pressure warning system is initialized, the current tire inflation
pressure is set as the benchmark pressure.
Tire pressure warning system
●The tire pressure detected by the tire
pressure warning system can be dis-
played on the multi-information display.
The illustration used is intended as an exam-
ple, and may differ from the image that is
actually displayed on the multi-information
display.
●If the tire pressure drops below a prede-
termined level, the driver is warned by a
screen display and a warning light.
( P. 656)
The illustration used is intended as an exam-
ple, and may differ from the image that is
actually displayed on the multi-information
display.

6067-3. Do-it-yourself maintenance
RX350/RX350L_U
■How to initialize the tire pressure warning system Park the vehicle in a safe place and turn the engine switch off.
Initialization cannot be performed while the vehicle is moving.
Adjust the tire inflation pressure to th e specified cold tire inflation pressure
level. ( P. 704)
Make sure to adjust the tire pressure to the specified cold tire inflation pressure
level. The tire pressure warning system will operate based on this pressure level.
Turn the engine switch to IGNITION ON mode.
Select on the multi-information display. ( P. 97)
Press or of the meter control sw itch, select the “Vehicle Settings”
screen and then press the .
Press or of the meter con-
trol switch, select the “TPMS”
screen and then press and hold
the
until the tire pressure
warning light blinks slowly 3
times.
“- -” will be displayed for inflation
pressure of each tire on the multi-
information displa y while the tire
pressure warning system determines
the position of each tire.
When position of each tire is determined, the inflation pressure of each tire will be
displayed on the mult i-information display.
Drive the vehicle at approximately 25 mph (40 km/h) or more for approx-
imately 10 to 30 minutes until the inflat ion pressure of each tire is displayed
on the multi-information display.
If tire inflation pressure becomes low before the inflation pressure is displayed, the
tire pressure warning light will come on.
Depending on the vehicle and driving co nditions, initialization may take up to
approximately 1 hour to complete.
◆Registering ID codes
The tire pressure warning valve and tran smitter is equipped with a unique ID
code. When replacing a tire pressure warning valve and transmitter, it is nec-
essary to register the ID code. Have the ID code registered by your Lexus
dealer.
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6077-3. Do-it-yourself maintenance
7
Maintenance and care
RX350/RX350L_U
■When to replace your vehicle’s tires
Tires should be replaced if:
●The treadwear indicators are showing on a tire.
●You have tire damage such as cuts, splits, cracks deep enough to expose the fabric, and
bulges indicating internal damage.
●A tire goes flat repeatedly or cannot be properly repaired due to the size or location of
a cut or other damage.
If you are not sure, consult with your Lexus dealer.
■Replacing tires and wheels
If the ID code of the tire pressure warning valve and transmitter is not registered, the tire
pressure warning system will not work proper ly. After driving for about 20 minutes, the
tire pressure warning light blinks for 1 minu te and stays on to indicate a system malfunc-
tion.
■Tire life
Any tire over 6 years old must be checked by a qualified technician even if it has seldom
or never been used or damage is not obvious.
■Proper storage of the spare tire (RX350L)
As an improperly stored spare tire may cause damage to the wire cable that holds it,
check that the spare tire is stored properly on a daily basis.
If the spare tire is slanted, the hoist assemb ly may be stuck in the wheel opening. If the
spare tire rattles while driving, it may not be fully raised. Lower the spare tire to the
ground and make sure that the hoist assemb ly is perpendicular to the wheel opening.
Raise the tire slowly and steadily until a click is heard and the jack handle skips.
If the spare tire cannot be lowered, the wire cable may be severed. Have the vehicle
inspected at your Lexus dealer.
■Routine tire inflation pressure checks
The tire pressure warning syst em does not replace routine tire inflation pressure checks.
Make sure to check tire inflat ion pressure as part of your routine of daily vehicle checks.
●If the stored spare tire appears to be slanted or
rattles while driving, the spare tire may not be
properly stored. Store the spare tire again by
performing the following tire change proce-
dure correctly:
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6097-3. Do-it-yourself maintenance
7
Maintenance and care
RX350/RX350L_U
■Situations in which the tire pressure warning system may not operate properly
●In the following cases, the tire pressure warning system may not operate properly.
• If non-genuine Lexus wheels are used.
• A tire has been replaced with a tire that is not an OE (Original Equipment) tire.
• A tire has been replaced with a tire that is not of the specified size.
• Tire chains, etc. are equipped.
• If a window tint that affects th e radio wave signals is installed.
• If there is a lot of snow or ice on the vehi cle, particularly around the wheels or wheel
housings.
• If the tire inflation pressure is extr emely higher than the specified level.
• If wheel without the tire pressure warning valve and transmitter is used.
• If the ID code on the tire pressure warning valves and transmitters is not registered in the tire pressure warning computer.
●Performance may be affected in the following situations.
• Near a TV tower, electric power plant, gas station, radio station, large display, air-
port or other facility that generates st rong radio waves or electrical noise.
• When carrying a portable radio, cellular phone, cordless phone or other wireless
communication device.
If tire position information is not correctly displayed due to the radio wave conditions,
the display may be corrected by driving and changing the radio wave conditions.
●When the vehicle is parked, the time taken for the warning to start or go off could be
extended.
●When tire inflation pressure declines rapidly for example when a tire has burst, the
warning may not function.
■The initialization operation
●Make sure to carry out initialization afte r adjusting the tire inflation pressure.
Also, make sure the tires are cold before carryi ng out initialization or tire inflation pres-
sure adjustment.
●If you have accidentally turned the engine swit ch off during initialization, it is not neces-
sary to press the reset switch again as initialization will restart automatically when the
engine switch has been turned to IG NITION ON mode for the next time.
●If you accidentally press the reset switch when initialization is not necessary, adjust the
tire inflation pressure to the specified leve l when the tires are cold, and conduct initial-
ization again.
●While the position of each tire is being de termined and the inflation pressures are not
being displayed on the multi-info rmation display, if the inflation pressure of a tire drops,
the tire pressure warning light will come on.