overheating LEXUS UX250H 2019 Owners Manual

681-4. Hybrid system
battery) may overheat, leading to a
reduction in hybrid battery (traction
battery) output.
When a certain level of impact is
detected by the impact sensor, the
emergency shut off system blocks the
high voltage current and stops the fuel
pump to minimize the risk of electrocu-
tion and fuel leakage. If the emergency
shut off system activates, your vehicle
will not restart. To restart the hybrid
system, contact your Lexus dealer.
A message is automatically displayed when a malfunction occurs in the
hybrid system or an improper opera-
tion is attempted.
If a warning message is shown on the
multi-information display, read the
message and follow the instructions.
■If a warning light comes on, a warning
message is displayed, or the 12-volt bat-
tery is disconnected
The hybrid system may not start. In this
case, try to start the system again. If the
“READY” indicator does not come on, con-
tact your Lexus dealer.
NOTICE
■Hybrid battery (traction battery) air
intake vent
●Make sure not to block the air intake
vent with anything, such as a seat
cover, luggage or carpet. The hybrid
battery (traction battery) may over-
heat, leading to poor fuel economy.
●Clean the air intake vent regularly to
prevent the hybrid battery (traction
battery) from overheating.
●Do not get water or foreign materials
in the air intake vent as this may cause
a short circuit and damage the hybrid
battery (traction battery).
●A filter is installed to the air intake vent.
When the filter remains noticeably
dirty even after cleaning the air intake
vent, filter cleaning or replacement is
recommended. When cleaning or
replacing the filter, contact your Lexus
dealer.
Refer to P.365 for details on how to
clean the filter.
Emergency shut off system
Hybrid warning message

802-1. Instrument cluster
( P.435)
■Display items
 Odometer
Displays the total distance the vehicle has
been driven.
Trip meter A/trip meter B
Displays the distance the vehicle has been
driven since the meter was last reset. Trip
meters A and B can be used to record and display different distances independently.

Distance until next engine oil
change
Displays the distance the vehicle can be
driven until an oil change is necessary.
■Changing the display
Each time the “ODO TRIP” switch is
pressed, the displayed item will be
changed. When the trip meter is dis-
played, pressing and holding the switch
will reset the trip meter.
■Pop-up display
Distance until the next engine oil
change will displayed when a warning
message indicating that oil mainte-
nance should be performed soon or is
required is displayed.
The brightness of the instrument panel
lights can be adjusted.
WARNING
■The information display at low tem-
peratures
Allow the interior of the vehicle to warm
up before using the liquid crystal infor-
mation display. At extremely low tem-
peratures, the information display
monitor may respond slowly, and display
changes may be delayed.
For example, there is a lag between the
driver’s shifting and the new gear number
appearing on the display. This lag could
cause the driver to downshift again,
causing rapid and excessive engine brak-
ing and possibly an accident resulting in
death or injury.
NOTICE
■To prevent damage to the engine and
its components
●Do not let the indicator of the tachom-
eter enter the red zone, which indi-
cates the maximum engine speed.
●The engine may be overheating if the
engine coolant temperature gauge is
in the red zone (H). In this case, imme-
diately stop the vehicle in a safe place,
and check the engine after it has
cooled completely. ( P.410)
Odometer and trip meter dis-
playChanging the instrument panel
light brightness

852-1. Instrument cluster
2
Vehicle status information and indicators
■Engine speed
On hybrid vehicles, engine speed is pre-
cisely controlled in order to help improve
fuel efficiency and reduce exhaust emis-
sions etc.
There are times when the engine speed that
is displayed may differ even when vehicle
operation and driving conditions are the
same.
■Hybrid System Indicator is displayed
when
The Hybrid System Indicator is displayed in
the following situations:
●The shift lever is in D or S.
●The driving mode is other than Sport
mode.
■Outside temperature display
●In the following situations, the correct
outside temperature may not be dis-
played, or the display may take longer
than normal to change:
• When stopped, or driving at low speeds (less than 12 mph [20 km/h])
• When the outside temperature has changed suddenly (at the entrance/exit of
a garage, tunnel, etc.)
●When “--” or “E” is displayed, the system
may be malfunctioning. Take your vehicle
to your Lexus dealer.
■Speed unit setting for the speedometer
When the speed unit has been changed
from the default setting, the vehicle speed in
the default unit is also displayed in the
meter.
■Liquid crystal display
 P.88
■Customization
The gauges and meters can be customized
on of the multi-information display.
(  P.435)
WARNING
■The information display at low tem-
peratures
Allow the interior of the vehicle to warm
up before using the liquid crystal infor-
mation display. At extremely low tem-
peratures, the information display
monitor may respond slowly, and display
changes may be delayed.
For example, there is a lag between the
driver’s shifting and the new gear number
appearing on the display. This lag could
cause the driver to downshift again,
causing rapid and excessive engine brak-
ing and possibly an accident resulting in
death or injury.
NOTICE
■To prevent damage to the engine and
its components
●Do not let the indicator of the tachom-
eter enter the red zone, which indi-
cates the maximum engine speed.
●The engine may be overheating if the
engine coolant temperature gauge is
in the red zone (H). In this case, imme-
diately stop the vehicle in a safe place,
and check the engine after it has
cooled completely. ( P.410)

1564-1. Before driving
WARNING
●Always apply the parking brake, shift
the shift lever to P, stop the hybrid sys-
tem and lock the vehicle.
Do not leave the vehicle unattended
while the “READY” indicator is illumi-
nated.
If the vehicle is parked with the shift
lever in P but the parking brake is not
set, the vehicle may start to move, pos-
sibly leading to an accident.
●Do not touch the exhaust pipes while
the “READY” indicator is illuminated
or immediately after turning the hybrid
system off.
Doing so may cause burns.
■When taking a nap in the vehicle
Always turn the hybrid system off. Other-
wise, if you accidentally move the shift
lever or depress the accelerator pedal,
this could cause an accident or fire due
to hybrid system overheating. Addition-
ally, if the vehicle is parked in a poorly
ventilated area, exhaust gases may col-
lect and enter the ve hicle, leading to
death or a serious health hazard.
■When braking
●When the brakes are wet, drive more
cautiously.
Braking distance increases when the
brakes are wet, and this may cause one
side of the vehicle to brake differently
than the other side. Also, the parking
brake may not securely hold the vehi-
cle.
●If the electronically controlled brake
system does not operate, do not follow
other vehicles closely and avoid hills or
sharp turns that require braking.
In this case, braking is still possible, but
the brake pedal should be depressed
more firmly than usual. Also, the brak-
ing distance will increase. Have your
brakes fixed immediately.
●The brake system consists of 2 or more
individual hydraulic systems; if one of
the systems fails, the other(s) will still
operate. In this case, the brake pedal
should be depressed more firmly than
usual and the braking distance will
increase. Have your brakes fixed
immediately.
■If the vehicle becomes stuck (AWD
models)
Do not spin the wheels excessively when
any of the tires is up in the air, or the vehi-
cle is stuck in sand, mud, etc. This may
damage the driveline components or
propel the vehicle forward or backward,
causing an accident.
NOTICE
■When driving the vehicle
●Do not depress the accelerator and
brake pedals at the same time during
driving, as this may restrain the hybrid
system output.
●Do not use the accelerator pedal or
depress the accelerator and brake
pedals at the same time to hold the
vehicle on a hill.
■Avoiding damage to vehicle parts
●Do not turn the steering wheel fully in
either direction and hold it there for an
extended period of time.
Doing so may damage the power
steering motor.
●When driving over bumps in the road,
drive as slowly as possible to avoid
damaging the wheels, underside of the
vehicle, etc.
■If you get a flat tire while driving
A flat or damaged tire may cause the fol-
lowing situations. Hold the steering
wheel firmly and gradually depress the
brake pedal to slow down the vehicle.
●It may be difficult to control your vehi-
cle.

1634-2. Driving procedures
4
Driving
■Steering lock function
●After turning the power switch off and
opening and closing the doors, the steer-
ing wheel will be locked due to the steer-
ing lock function. Operating the power
switch again automatically cancels the
steering lock.
●When the steering lock cannot be
released, “Push Power Switch while Turn-
ing Steering Wheel in Either Direction”
will be displayed on the multi-information
display.
Check that the shift lever is in P. Press the
power switch shortly and firmly while
turning the steering wheel left and right.
●To prevent the steering lock motor from
overheating, operation of the motor may
be suspended if the hybrid system is
turned on and off repeatedly in a short
period of time. In this case, refrain from
operating the hybrid system. After about
10 seconds, the steering lock motor will
resume functioning.
■If the “READY” indicator does not come
on
In the event that the “READY” indicator
does not come on even after performing
the proper procedures for starting the vehi-
cle, contact your Lexus dealer immediately.
■If the hybrid system is malfunctioning
 P.68
■Electronic key battery
 P.368
■Operation of the power switch
●If the switch is not pressed shortly and
firmly, the power switch mode may not
change or the hybrid system may not
start.
●If attempting to restart the hybrid system
immediately after turning the power switch off, the hybrid system may not start
in some cases. After turning the power
switch off, please wait a few seconds
before restarting the hybrid system.
■Customization
If the smart access system with push-button
start has been deactivated in a customized
setting, refe r to P.403
1Stop the vehicle completely.
WARNING
■When starting the hybrid system
Always start the hybrid system while sit-
ting in the driver’s seat. Do not depress
the accelerator pedal while starting the
hybrid system under any circumstances.
Doing so may cause an accident result-
ing in death or serious injury.
■Caution while driving
If hybrid system failure occurs while the
vehicle is moving, do not lock or open the
doors until the vehicle reaches a safe and
complete stop. The steering lock func-
tion will activate and this may lead to an
accident, resulting in death or serious
injury.
NOTICE
■When starting the hybrid system
If the hybrid system becomes difficult to
start, have your vehicle checked by your
Lexus dealer immediately.
■Symptoms indicating a malfunction
with the power switch
If the power switch seems to be operat-
ing somewhat differently than usual, such
as the switch sticking slightly, there may
be a malfunction. Contact your Lexus
dealer immediately.
Stopping the hybrid system

1734-2. Driving procedures
4
Driving
ing brake
• Operate the parking brake switch while depressing the brake pedal.
• Using the parking brake automatic release function, the parking brake can
be released by depressing the accelera-
tor pedal. When using this function,
slowly depress the accelerator pedal.
Make sure that the pa rking brake indicator
light turn off.
■Turning the automatic mode on
While the vehicle is stopped, press and
hold the parking brake switch until a
message is shown on the multi-infor-
mation display
When the automatic mode is turned
on, the parking brake operates as fol-
lows.
 When the shift lever is shifted from
P, the parking brake will be released,
and the parking brake indicator light
will turn off.
 When the shift lever is shifted to P,
the parking brake will be set, and the
parking brake indicator light will
turn on.
Operate the shift lever with the vehicle
stopped and the brake pedal
depressed.
■Turning the automatic mode off
While the vehicle is stopped, pull and
hold the parking brake switch until a
message is shown on the multi-infor-
mation display
■Parking brake operation
●When the power switch is not in ON, the
parking brake cannot be released using
the parking brake switch.
●When the power swit ch is not in ON,
automatic mode (automatic brake setting
and releasing) is not available.
■Parking brake automatic release func-
tion
●When the shift lever is shifted from P, the
parking brake will be released in auto-
matic mode.
●When all of the follo wing conditions are
met in manual mode, the parking brake
can be released by depressing the accel-
erator pedal.
• The driver’s door is closed
• The driver is wearing the seat belt
• The shift lever is in D, S or R
■If “Parking Brake Temporarily Unavail-
able” is displayed on the multi-informa-
tion display
If the parking brake is operated repeatedly
over a short period of time, the system may
restrict operation to prevent overheating. If
this happens, refrain from operating the
parking brake. Normal operation will return
after about 1 minute.

1744-2. Driving procedures
■If “Parking Brake Unavailable” or “EPB
Unavailable” is displayed on the multi-
information display
Operate the parking brake switch. If the
message does not disappear after operat-
ing the switch several times, the system may
be malfunctioning. Have the vehicle
inspected by your Lexus dealer.
■Parking brake operation sound
When the parking brake operates, a motor
sound (whirring sound) may be heard. This
does not indicate a malfunction.
■Parking brake indicator light
●Depending on the power switch mode,
the parking brake indi cator light will turn
on and stay on as described below:
ON: Comes on until the parking brake is
released.
Not in ON: Stays on for approximately 15
seconds.
●When the power switch is turned off with
the parking brake set, the parking brake
indicator light will stay on for about 15
seconds. This does not indicate a mal-
function.
■When the parking brake switch mal-
functions
Automatic mode (automatic brake setting
and releasing) will be turned on automati-
cally.
■Parking the vehicle
 P.152
■Parking brake engaged warning buzzer
A buzzer will sound if the vehicle is driven
with the parking brake engaged. “EPB
Applied” is displayed on the multi-informa-
tion display (with the vehicle reached a
speed of 3 mph [5 km/h]).
■If the brake system warning light comes
on
 P.386
■Usage in winter time
 P.263
WARNING
■When parking the vehicle
Do not leave a child in the vehicle alone.
The parking brake may be released unin-
tentionally and there is the danger of the
vehicle moving that may lead to an acci-
dent resulting in death or serious injury.
NOTICE
■When parking the vehicle
Before you leave the vehicle, shift the
shift lever to P, set the parking brake and
make sure that the vehicle does not
move.
■When the system malfunctions
Stop the vehicle in a safe place and
check the warning messages.
■When the parking brake cannot be
released due to a malfunction
Driving the vehicle with the parking
brake set will lead to brake components
overheating, which may affect braking
performance and increase brake wear.
Have the vehicle inspected by your
Lexus dealer immediately if this occurs.

2594-5. Using the driving support systems
4
Driving
systems are turned off, automatic re-
enabling will not occur when vehicle
speed increases.
■Secondary Collision Brake operating
conditions
The vehicle speed is approximately 6 mph
(10 km/h) or more and the airbag sensor
detects a collision. (The Secondary Colli-
sion Brake will not operate when the vehicle
speed is below approximately 6 mph [10
km/h].)
■Secondary Collision Brake automatic
cancellation
The Secondary Collision Brake is automati-
cally canceled in the following situations.
●The vehicle speed drops below approxi-
mately 6 mph (10 km/h)
●A certain amount of time elapses during
operation
●The accelerator pedal is depressed a
large amount
■Operating conditions of Active Corner-
ing Assist
The system operates in the following situa-
tions.
●TRAC/VSC can operate
●The system determines that the vehicle is
drifting to the outer side when attempting
to accelerate during cornering
●The brake pedal is released
■Reduced effectiveness of the EPS sys-
tem
The effectiveness of the EPS system is
reduced to prevent the system from over-
heating when there is frequent steering
input over an extended period of time. The
steering wheel may feel heavy as a result.
Should this occur, re frain from excessive
steering input or stop the vehicle and turn
the hybrid system off. The EPS system
should return to normal within 10 minutes.
■If a message about AWD system is
shown on the multi-information display
(AWD models)
If one of the following messages is shown on
the multi-information di splay, perform each
action.
●“AWD System Overheated Switching to
2WD Mode”
The AWD system is overheating. Reduce
load on the system by stopping the vehicle
for a while or driving the vehicle at a speed
of 6 mph (10 km/h) or more. If the message
disappears, it is possible to drive the vehicle
normally.
●“AWD System Overheated 2WD Mode
Engaged”
The AWD system has been canceled and
switched to the front-wheel drive due to
overheating. Reduce load on the system by
stopping the vehicle for a while or driving
the vehicle at a speed of 6 mph (10 km/h)
or more. If the message disappears, it is
possible to drive the vehicle normally.
●“AWD System Malfunction 2WD Mode
Engaged Visit Your Dealer”
The AWD system has been stopped and
switched to the front-wheel drive due to a
malfunction. Have your vehicle inspected
by your Lexus dealer immediately.
WARNING
■The ABS does not operate effectively
when
●The limits of tire gripping performance
have been exceeded (such as exces-
sively worn tires on a snow covered
road).
●The vehicle hydroplanes while driving
at high speed on wet or slick road.
■Stopping distance when the ABS is
operating may exceed that of normal
conditions
The ABS is not designed to shorten the
vehicle’s stopping distance. Always main-
tain a safe distance from the vehicle in
front of you, especially in the following
situations:
●When driving on dirt, gravel or snow-
covered roads

2875-3. Using the air conditioning system and defogger
5
Interior features
■Seat heaters
Turns the seat heaters on/off
Each time the switch is pressed, the opera-
tion condition changes as follows.
AUTO (lit)  Hi (3 segments lit)  Mid
(2 segments lit)  Lo (1 segment lit) 
Off
The AUTO indicator and/or level indi-
cator illuminates during operation.
■Seat ventilators
Turns the seat ventilators on/off
Each time the switch is pressed, the opera-
tion condition changes as follows.
AUTO (lit)  Hi (3 segments lit)  Mid
(2 segments lit)  Lo (1 segment lit) 
Off
The AUTO indicator and/or level indi-
cator illuminates during operation.
■The seat ventilators can be used when
The power switch is in ON.
■Air conditioning system-linked control
mode
When the seat ventilator fan speed level is
Hi, the seat ventilator fan speed becomes
higher according to the fan speed of the air
conditioning system.
■Customization
Settings for the seat heaters and ventilators
can be changed. (Customizable features:
 P.443)
■Main display
Using the touchpad of the Remote
Touch, select the button on the screen.
to can be adjusted by perform-
ing the following operations.
Flick operation: Move the pointer to
the desired item and flick the touchpad
Seat heaters and ventilators
(front seats)
A
B
A
B
WARNING
■To prevent causes of overheating and
minor burn injuries
Observe the following precautions when
using the seat heaters.
●Do not cover the seat with a blanket or
cushion when using the seat heater.
●Do not use seat heater more than nec-
essary.
Control screen
AC

4107-2. Steps to take in an emergency
If the engine coolant temperature
gauge enters the red zone or
“Engine Coolant Temp High Stop in
a Safe Place See Owner’s Manual”
is shown on the multi-information
display
1
Stop the vehicle in a safe place and
turn off the air conditioning system,
and then stop the hybrid system.
2
If you see steam:
Carefully lift the hood after the
steam subsides.
If you do not see steam:
Carefully lift the hood.
3
After the hybrid system has cooled
down sufficiently, inspect the hoses
WARNING
■When replacing the 12-volt battery
●When the vent plug is close to the hold
down clamp, the battery fluid (acid)
may leak.
●For information regarding battery
replacement, contact your Lexus
dealer.
●After exchanging, securely attach the
elbow connected to the exhaust hose,
and exhaust hole plug to the exhaust
hole of the exchanged 12-volt battery.
If not properly installed, gases (hydro-
gen) may leak into the vehicle interior,
and there is the possible danger of the
gas igniting and exploding.
NOTICE
■When handling jumper cables
When connecting the jumper cables,
ensure that they do not become entan-
gled in the cooling fans or belt.
■To prevent damaging the vehicle
The exclusive jump starting terminal is to
be used when charging the 12-volt bat-
tery from another vehicle in an emer-
gency. It cannot be used to jump start
another vehicle.
If your vehicle overheats
The following may indicate that
your vehicle is overheating.
 The engine coolant temperature
gauge ( P.78, 82) enters the
red zone, or a loss of hybrid sys-
tem power is experienced. (For
example, the vehicle speed does
not increase.)
 “Engine Coolant Temp High Stop
in a Safe Place See Owner’s
Manual” or “Hybrid system over-
heated Output power reduced” is
shown on the multi-information
display.
 Steam comes out from under the
hood.
Correction procedures