Page 521 of 628

5078-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53B95E)
If a warning light turns on or a warning buzzer sounds
Calmly perform the following actions if any of the warning lights comes
on or flashes. If a light comes on or flashes, but then goes off, this does
not necessarily indicate a malfunction in the system. However, if this
continues to occur, have the vehicle inspected by any authorized Lexus
dealer or repairer, or another duly qualified and equipped professional.
Warning light and warning buzzer list
Warning lightWarning light/Details/Actions
Brake system warning light (warning buzzer)*1
Indicates that:
• The brake fluid level is low; or
• The brake system is malfunctioning
Immediately stop the vehicle in a safe place and contact any
authorized Lexus dealer or repairer, or another duly quali-
fied and equipped professional. Continuing to drive the
vehicle may be dangerous.
Brake system warning light
Indicates a malfunction in:
• The regenerative braking system; or
• The electronically controlled brake system
Have the vehicle inspected by any authorized Lexus dealer
or repairer, or another duly qualified and equipped profes-
sional immediately.
Charging system warning light
Indicates a malfunction in the vehicle’s charging system
Immediately stop the vehicle in a safe place and contact any
authorized Lexus dealer or repairer, or another duly quali-
fied and equipped professional.
Malfunction indicator lamp
Indicates a malfunction in:
• The hybrid system;
• The emission control system (if equipped);
• The electronic engine control system; or
• The electronic throttle control system
Have the vehicle inspected by any authorized Lexus dealer
or repairer, or another duly qualified and equipped profes-
sional immediately.
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5098-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53B95E)
Automatic headlight leveling system warning light
Indicates a malfunction in the automatic headlight leveling
system
Have the vehicle inspected by any authorized Lexus dealer
or repairer, or another duly qualified and equipped profes-
sional immediately.
Open door warning light (warning buzzer)*2
Indicates that a door or the trunk is not fully closed
Check that all the doors and the trunk are closed.
Low fuel level warning light
Indicates that remaining fuel is approximately 10 L (2.6 gal.,
2.2 Imp. gal.) or less
Refuel the vehicle.
Driver’s and front passenger’s seat belt reminder light (warn-
ing buzzer)
*3
Warns the driver and/or front passenger to fasten their seat
belts
Fasten the seat belt.
If the front passenger’s seat is occupied, the front passen-
ger’s seat belt also needs to be fastened to make the warning
light (warning buzzer) turn off.
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
malfunction.
P. 5 1 4
Warning lightWarning light/Details/Actions
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5128-2. Steps to take in an emergency
IS300h_EE(OM53B95E)
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 dealer or repairer, or another duly qualified and equipped professional.
Warning buzzer
In some cases, the buzzer may not be heard due to being in a noisy location or
audio sound.
CAUTION
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
dealer or repairer, or another duly qualified and equipped professional. 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
The steering wheel may become extremely heavy.
If the steering wheel becomes heavier than usual when operating, hold firmly
and operate using more force than usual.
If the tire pressure warning light comes on
Be sure to observe the following precautions. 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
adjustment, it is probable that you have 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
adjustment, it is probable that you have a flat tire. Have the tire replaced by
the nearest authorized Lexus dealer or repairer, or another duly qualified and
equipped professional.
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 system may not activate immediately.
Page 528 of 628
5148-2. Steps to take in an emergency
IS300h_EE(OM53B95E)
Master warning light
The master warning light also comes on or flashes in order to indicate that a
message is currently being displayed on the multi-information display.
Multi-information display
If any of the warning lights come on again after the following actions
have been performed, contact any authorized Lexus dealer or repairer, or
another duly qualified and equipped professional.
If a warning message is displayed
If a warning is shown on the multi-information display, stay calm and
perform the following actions:
Except F SPORT modelsF SPORT models (when the main
meter is in the center position)
F SPORT models (when the
main meter is in the right-side
position)
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Page 535 of 628

5218-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53B95E)
Indicates that the power switch is turned off or
turned to ACCESSORY mode and the driver’s door
is opened while the lights are turned on
A buzzer also sounds.
Turn the lights off.
(If equipped)
Indicates that the moon roof is not fully closed
(with the power switch off, and the driver’s door
open)
A buzzer also sounds.
Close the moon roof.
Indicates that the windows are not fully closed
(with the power switch off, and the driver’s door
open)
A buzzer also sounds.
Close all the windows.
(If equipped)
Indicates that the windows and the moon roof are
not fully closed (with the power switch off, and the
driver’s door open)
A buzzer also sounds.
Close all the windows and the moon roof.
Indicates a malfunction in the brake override sys-
tem
A buzzer also sounds.
Have the vehicle inspected by any authorized
Lexus dealer or repairer, or another duly quali-
fied and equipped professional.
Indicates that engine oil level is low
A buzzer also sounds.
Check the level of engine oil, and add if neces-
sary.
Indicates that the hybrid system has overheated
This message may be displayed when driving
under severe operating conditions. (For example,
when driving up a long steep hill.)
A buzzer also sounds.
Stop and check. (P. 556)
Warning messageDetails/Actions
(Flashes)
(Flashes)
(Flashes)
(Flashes)
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5238-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53B95E)
(If equipped)
Indicates that the Automatic High Beam switch is
pressed while the headlights are in low beam.
Turn the high beam on and press the Automatic
High Beam switch again.
(If equipped)
Indicates that, since the VSC (Vehicle Stability
Control) system was turned off, the pre-crash brake
system operation is stopped
Turn the VSC on. (P. 295)
(If equipped)
Indicates that the PCS (Pre-Crash Safety system) is
not currently functional because the grille cover or
the sensor is dirty
Check the grille cover and the sensor and clean
them if they are dirty.
Indicates that operation of large electricity consum-
ing systems such as the air conditioning system are
suspended
Stop using unnecessary electric components to
reduce electricity consumption. Wait a while
until the electric power supply is restored.
(If equipped)
Indicates that the LDA (Lane Departure Alert) sys-
tem cannot be used because the vehicle speed is
lower than approximately 50 km/h (32 mph)
Drive the vehicle at 50 km/h (32 mph) or higher.
Warning messageDetails/Actions
(Flashes)
Page 560 of 628

5468-2. Steps to take in an emergency
IS300h_EE(OM53B95E)
One of the following may be the cause of the problem:
The electronic key may not be functioning properly. (P. 550)
There may not be sufficient fuel in the vehicle’s tank.
Refuel the vehicle.
There may be a malfunction in the immobilizer system. (P. 9 0 )
There may be a malfunction in the steering lock system.
The hybrid system may be malfunctioning due to an electrical problem
such as electronic key battery depletion or a blown fuse. However,
depending on the type of malfunction, an interim measure is available
to start the hybrid system. (P. 547)
One of the following may be the cause of the problem:
The 12-volt battery terminal connections may be loose or corroded.
The 12-volt battery may be discharged. (P. 551)
If the hybrid system will not start
Reasons for the hybrid system not starting vary depending on the situa-
tion. Check the following and perform the appropriate procedure:
The hybrid system will not start even though the correct starting
procedure is being followed. (P. 209)
The interior lights and headlights are dim, or the horn does not
sound or sounds at a low volume.
Page 561 of 628

5478-2. Steps to take in an emergency
8
When trouble arises
IS300h_EE(OM53B95E)
One of the following may be the cause of the problem:
One or both of the 12-volt battery terminals may be disconnected.
The 12-volt battery may be discharged. (P. 551)
Contact any authorized Lexus dealer or repairer, or another duly qualified and
equipped professional if the problem cannot be repaired, or if repair proce-
dures are unknown.
When the hybrid system does not start, the following steps can be used as
an interim measure to start the hybrid system if the power switch is func-
tioning normally:
Set the parking brake.
Shift the shift lever to P.
Turn the power switch to ACCESSORY mode.
Press and hold the power switch for about 15 seconds while depressing
the brake pedal firmly.
Even if the hybrid system can be started using the above steps, the system
may be malfunctioning. Have the vehicle inspected by any authorized
Lexus dealer or repairer, or another duly qualified and equipped profes-
sional.
The interior lights and headlights do not turn on, or the horn does
not sound.
Emergency start function
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