
5437-3. Do-it-yourself maintenance
7
Maintenance and care
IS300h_EE(OM53D89E)
■Effects of incorrect tire inflation pressure
Driving with incorrect tire inflation pressure may result in the following:
●Reduced fuel economy
●Reduced driving comfort and poor handling
●Reduced tire life due to wear
●Reduced safety
●Damage to the drivetrain
If a tire needs frequent inflating, have it checked by any authorized Lexus retailer or
Lexus authorized repairer, or any reliable repairer.
■Instructions for checking tire inflation pressure
When checking tire inflation pressure, observe the following:
●Check only when the tires are cold. If your vehicle has been parked for at least 3 hours or has not been driven for more than
1.5 km or 1 mile, you will ge t an accurate cold tire inflation pressure reading.
●Always use a tire pressure gauge. It is difficult to judge if a tire is prop erly inflated based only on its appearance.
●It is normal for the tire inflation pressure to be higher after driving as heat is generated
in the tire. Do not reduce tire inflation pressure after driving.
●Passengers and luggage weight should be placed so that the vehicle is balanced.
Tire inflation pressure
Make sure to maintain proper tire inflation pressure. Tire inflation pressure
should be checked at least once pe r month. However, Lexus recommends
that tire inflation pressure be checked once every two weeks. (P. 652)

5447-3. Do-it-yourself maintenance
IS300h_EE(OM53D89E)
WARNING
■Proper inflation is critical to save tire performance
Keep your tires properly inflated.
If the tires are not properly inflated, the following conditions may occur which could
lead to an accident resultin g in death or serious injury:
●Excessive wear
●Uneven wear
●Poor handling
●Possibility of blowouts resulting from overheated tires
●Air leaking from between tire and wheel
●Wheel deformation and/or tire damage
●Greater possibility of tire damage while driving (due to road hazards, expansion
joints, sharp edges in the road, etc.)
NOTICE
■When inspecting and adjust ing tire inflation pressure
Be sure to put the tire valve caps back on.
If a valve cap is not installed, dirt or moisture may get into the valve and cause an air leak, resulting in decrease d tire inflation pressure.

5457-3. Do-it-yourself maintenance
7
Maintenance and care
IS300h_EE(OM53D89E)
When replacing wheels, care should be taken to ensure that they are equivalent
to those removed in load capacity, diameter, rim width and inset*.
Replacement wheels are available at any authorized Lexus retailer or Lexus
authorized repairer, or any reliable repairer.
*: Conventionally referred to as “offset”.
Lexus does not recommend using the following:
●Wheels of different sizes or types
●Used wheels
●Bent wheels that have been straightened
●Use only Lexus wheel nuts and wrenches designed for use with your alumi-
num wheels.
●When rotating, repairing or changing your tires, check that the wheel nuts are
still tight after driving 1600 km (1000 miles).
●Be careful not to damage the aluminum wheels when using tire chains.
●Use only Lexus genuine balance weights or equivalent and a plastic or rubber
hammer when balancing your wheels.
■When replacing wheels
The wheels of your vehicle are equipped with tire pressure warning valves and transmit- ters that allow the tire pressure warning system to provide advance warning in the event
of a loss in tire inflation pressure. Whenever wheels are replaced, tire pressure warning
valves and transmitters must be installed. (P. 526)
Wheels
If a wheel is bent, cracked or heavily corroded, it should be replaced. Other-
wise, the tire may separate from the wheel or cause a loss of handling control.
Wheel selection
Aluminum wheel precautions

565
8When trouble arises
IS300h_EE(OM53D89E)
8-1. Essential information
Emergency flashe rs ..................566
If your vehicle has to
be stopped in an
emergency................................. 567
8-2. Steps to take in an
emergency
If your vehicle needs to
be towed .....................................568
If you think something is
wrong ........................................... 574
If a warning light turns
on or a warning buzzer
sounds.......................................... 575
If a warning message is
displayed ..................................... 581
If you have a flat tire
(vehicles with
emergency tire puncture
repair kit) ..................................... 610
If you have a flat tire
(vehicles with run-flat
tires).............................................. 625
If the hybrid sy stem will not
start ............................................... 626
If the electronic key does
not operate properly ............. 628
If the 12-volt battery is
discharged .................................. 631
If your vehicle overheats ......... 636
If the vehicle becomes
stuck ...............................................641

5748-2. Steps to take in an emergency
IS300h_EE(OM53D89E)
●Fluid leaks under the vehicle.
(Water dripping from the air co nditioning after use is normal.)
●Flat-looking tires or uneven tire wear
●Engine coolant temperature gauge needle continually points higher than nor-
mal.
●Changes in exhaust sound
●Excessive tire squeal when cornering
●Strange noises related to the suspension system
●Pinging or other noises related to the hybrid system
●Engine missing, stumb ling or running roughly
●Appreciable loss of power
●Vehicle pulls heavily to one side when braking
●Vehicle pulls heavily to one side when driving on a level road
●Loss of brake effectiveness, spongy feeling, pedal almost touches the floor
If you think something is wrong
If you notice any of the following symptoms, your vehicle probably needs
adjustment or repair. Contact any au thorized Lexus retailer or Lexus autho-
rized repairer, or any reliable re pairer as soon as possible.
Visible symptoms
Audible symptoms
Operational symptoms

5788-2. Steps to take in an emergency
IS300h_EE(OM53D89E)
*1: Parking brake engaged warning buzzer:
P. 587
*2: Open door warning buzzer:
P. 583
*3: Seat belt warning buzzer:
The seat belt warning buzzer sounds to al ert the driver, front passenger and rear pas-
sengers that his or her seat belt is not fastened. The buzzer sounds for 30 seconds
after the vehicle reaches a speed of 20 km/h (12 mph). Then, if the seat belt is still unfastened, the buzzer w ill sound in a different tone for 90 more seconds.
■Front passenger detection sensor, seat belt reminder and warning buzzer
●If luggage is placed on the front passenger seat, the front passenger detection sensor
may cause the warning light to flash and the warning buzzer to sound even if a passen-
ger is not sitting in the seat.
●If a cushion is placed on the seat, the sens or may not detect a passenger, and the warn-
ing light may not operate properly.
■If the malfunction indicator lamp comes on while driving
The malfunction indicato r lamp will come on if the fuel tank becomes completely empty.
If the fuel tank is empty, refuel the vehi cle immediately. The malfunction indicator lamp
will go off after several trips.
If the malfunction indicator lamp does not go off, contact any authorized Lexus retailer or
Lexus authorized repairer, or any re liable repairer as soon as possible.
Rear passengers’ seat belt reminder lights (warning buzzer)*3
Warns the rear passengers to fasten their seat belts
Fasten the seat belt.
Master warning light
A buzzer sounds and the warning light comes on and flashes to indicate that the master warning system has detected a malfunc-
tion.
P. 581
Tire pressure warning light When the light comes on:
Low tire inflation pressure such as
• Natural causes ( P. 579) •Flat tire ( P. 610, 625)
Adjust the tire inflation pressure to the specified level.
The light will turn off after a few minutes. In case the light does not turn off even if the tire inflat ion pressure is adjusted, have the
system checked by any authorized Lexus retailer or Lexus
authorized repairer, or any reliable repairer. When the light comes on after blinking for 1 minute:
Malfunction in the tire pressure warning system
Have the system checked by any authorized Lexus retailer or Lexus authorized repairer, or any reliable repairer.
Warning lightWarning light/Details/Actions

5798-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53D89E)
■Electric power steering system warning light (warning buzzer)
When the 12-volt battery charge becomes insu fficient or the voltage temporarily drops, the electric power steering system warning light may come on and the warning buzzer
may sound.
■When the tire pressure warning light comes on
Carry out the following procedure after the tire temperature has lowered sufficiently.
●Check the tire inflation pressure an d adjust to the appropriate level.
●If the warning light does not go out even after several minutes, check that the tire infla- tion pressure is at the specifie d level and carry out initialization.
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 ma y 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 caus ed by temperature. In this case, adjusting the tire inflation pressure will turn off the warning light (after a few minutes).
■Conditions that the tire pressure warning system may not function properly
P. 529
■If the tire pressure warning light frequently comes on after blinking for 1 minute
If the tire pressure warning light frequently comes on after blinking for 1 minute when the
power switch is turned to ON mode, have it checked by any authorized Lexus retailer or Lexus authorized repairer, or any reliable repairer.
■Warning buzzer
In some cases, the buzzer ma y not be heard due to being in a noisy location or audio
sound.

5808-2. Steps to take in an emergency
IS300h_EE(OM53D89E)
WARNING
■If both the ABS and the brake system warning lights remain on
Stop your vehicle in a safe place immediately and contact any authorized Lexus retailer
or Lexus authorized repairer, or any re liable repairer. The vehicle will become
extremely unstable during braking, and the ABS system may fail, which could cause an accident resulting in de ath or serious injury.
■When the electric power steering system warning light comes on
The steering wheel may 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 precaution s. Failure to do so could cause a loss of
vehicle control and result in death or serious injury.
Vehicles with an emergency tire puncture repair kit
●Stop your vehicle in a safe place as soon as possible. Adjust the tire inflation pressure
immediately.
●If the tire pressure warning light comes on even after tire inflation pressure adjust- ment, it is probable that you ha ve a flat tire. Check the tires. If a tire is flat, repair the
flat tire by using emergency tire puncture repair kit.
●Avoid abrupt maneuvering and braking. If the vehicle tires deteriorate, you could lose control of the steering wheel or the brakes.
Vehicles with run-flat tires
●Decelerate to the lowest appropriate speed as soon as possible. Do not drive over 60 km/h (37 mph).
●Check and adjust the tire inflation pressure immediately.
●If the tire pressure warning light comes on even after tire inflation pressure adjust- ment, it is probable that you have a flat tire. Have the tire replaced by the nearest
authorized Lexus retailer or Lexus author ized repairer, or any reliable repairer.
●Avoid abrupt maneuvering and braking. If the vehicle tires deteriorate, you could lose control of the steering wheel or the brakes.
■If a blowout or sudden air leakage should occur
The tire pressure warning syst em may not activate immediately.
NOTICE
■To ensure the tire pressure warning system operates properly
Do not install tires with different specifications or makers, as the tire pressure warning system may not operate properly.