engine LEXUS UX250H 2019 Workshop Manual

3706-3. Do-it-yourself maintenance
1Turn the power switch off.
2 Open the fuse box cover.
Engine compartment: type A fuse
box
Push the tab in and lift the lid off.
Engine compartment: type B fuse
box
Push the tab in and lift the lid off.
Left side instrument panel
Remove the lid.
Luggage compartment
Remove the 12-volt battery cover
( P.343) and push the tab in and lift the
lid off.
3 Remove the fuse.
Only type A fuse can be removed using the
pullout tool.
4Check if the fuse is blown.
Replace the blown fuse with a new fuse of
an appropriate amperage rating. The
amperage rating can be found on the fuse
box lid.
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

3857-2. Steps to take in an emergency
7
When trouble arises
Fluid leaks under the vehicle
(Water dripping from the air condi-
tioning after use is normal.)
 Flat-looking tires or uneven tire
wear
 Engine coolant temperature gauge
needle continually points higher
than normal
 Changes in exhaust sound
 Excessive tire squeal when corner-
ing
 Strange noises related to the sus-
pension system
 Pinging or other noises related to
the hybrid system
 Engine missing, stumbling or run-
ning 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. Con-
tact your Lexus dealer as soon as
possible.
Visible symptoms
Audible symptoms
Operational symptoms

3867-2. Steps to take in an emergency
■Brake system warning light (warning buzzer)
■Charging system warning light* (warning buzzer)
*: This light illuminates on the multi-information display.
■Low engine oil pressure warning light* (warning buzzer)
*: This light illuminates on the multi-information display.
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, bu t then goes off, this does not necessar-
ily indicate a malfunction in the system. However, if this continues to occur,
have the vehicle inspected by your Lexus dealer.
Actions to the warning lights or warning buzzers
Warning lightDetails/Actions
(U.S.A.)
or
(red)
(Canada)
Indicates that:
 The brake fluid level is low; or
 The brake system is malfunctioning
 Immediately stop the vehicle in a safe place and contact your Lexus
dealer. Continuing to drive the vehicle may be dangerous.
Warning lightDetails/Actions
Indicates a malfunction in the vehicle’s charging system
 Immediately stop the vehicle in a safe place and contact your Lexus
dealer.
Warning lightDetails/Actions
Indicates that the engine oil pressure is too low
 Immediately stop the vehicle in a safe place and contact your Lexus
dealer.

3877-2. Steps to take in an emergency
7
When trouble arises
■Malfunction indicator lamp (warning buzzer)
■High coolant temperature warning light* (warning buzzer)
*: This light illuminates on the multi-information display.
■Tire pressure warning light
■Brake system warning light (warning buzzer)
Warning lightDetails/Actions
(U.S.A.)
or
(Canada)
Indicates a malfunction in:
The hybrid system;
 The electronic engine control system; or
 The electronic throttle control system
 Immediately stop the vehicle in a safe place and contact your Lexus
dealer.
Warning lightDetails/Actions
Indicates that the engine coolant temperature is too high
 Immediately stop the vehicle in a safe place.
Handling method ( P.410)
Warning lightDetails/Actions
When the light comes on after bl inking for approximately 1 minute:
Malfunction in the tire pressure warning system
 Have the system checked by your Lexus dealer.
When the light comes on:
Low tire inflation pressure such as
 Natural causes
 Flat tire
 P.393
Warning lightDetails/Actions
(yellow)
Indicates a malfunction in:
The regenerative braking system;
 The electronically controlled brake system; or
 The parking brake system
 Have the vehicle inspected by your Lexus dealer immediately.

3967-2. Steps to take in an emergency
The warning lights and warning buzzers operate as follows depending on the con-
tent of the message. If a message indicates the need for inspection by a dealer, have
the vehicle inspected by your Lexus dealer immediately.
*: A buzzer sounds the first time a message is shown on the multi-information display.
■Warning messages
The warning messages explained below
may differ from the actual messages
according to operation conditions and vehi-
cle specifications.
■Warning buzzer
In some cases, the bu zzer may not be heard
due to being in a noisy location or audio
sound.
■If “Engine Oil Level Low Add or
Replace” is displayed
The engine oil level is low. Check the level
of the engine oil, and add if necessary.
This message may appear if the vehicle is
stopped on a slope. Move the vehicle to a
level surface and check to see if the mes-
sage disappears.
■If “Hybrid System Stopped Steering
Power Low” is displayed
This message is displayed if the hybrid sys-
tem is stopped while driving.
When steering wheel operations are
heavier than usual, gr ip the steering wheel
firmly and operate it using more force than
usual.
■If “Hybrid system overheated Output
power reduced” is displayed
This message may be displayed when driv-
ing under severe operat ing conditions. (For
example, when driving up a long steep hill.)
Handling method: P.410
■If “Traction Battery Needs to be Pro-
tected Refrain From the Use of N Posi-
tion” is displayed
This message may be displayed when the
shift lever is in N.
As the hybrid battery (traction battery) can-
Messages and warnings
Warning lightWarning buzzer*Warning
Sounds
• Indicates an important situation, such as when a system related to drivin g is malfunctioning or
that danger may result if the correction proce-
dure is not performed
• Indicates a situation, such as when damage to the vehicle or danger may result
Comes onor flashesSounds
Indicates an important situation, such as when the
systems shown on the multi-information display
may be malfunctioning
Does not sound
• Indicates a condition, such as malfunction of electrical components, th eir condition, or indi-
cates the need for maintenance
• Indicates a situation, such as when an operation has been performed incorrectly, or indicates
how to perform an operation correctly

3987-2. Steps to take in an emergency
reset. If necessary, perform maintenance.
Please reset the message after the mainte-
nance is performed. (P.328)
*: 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
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.328)
*: Refer to the separa te “Scheduled Main-
tenance” or “Owner’s Manual Supple-
ment” for the maintenance 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 and change it if neces-
sary. After changing the engine oil, make
sure to reset the message. ( P.339)
■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 deal er. After changing the
engine oil, make sure to reset the message.
(  P.339)
■If a message that in dicates 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
●If any of the following messages are
shown on the multi-information display,
follow the instructions.
• “Engine Coolant Temp High” ( P.410)
• “Front Camera Unavailable” ( P.196)
• “Radar Cruise Control Unavailable” ( P.196)
●If any of the following messages are
shown on the multi-info rmation display, it
may indicate a malf unction. Have the
vehicle inspected by your Lexus dealer
immediately.
• “Access System with Elec. Key Malfunc-
tion”
• “Hybrid system malfunction”
•“Check Engine”
• “Hybrid battery system malfunction”
• “Accelerator system malfunction”
●If any of the following messages are
shown on the multi-info rmation display, it
may indicate a malfun ction. Immediately
stop the vehicle and contact your Lexus
dealer.
• “Braking Power Low”
• “Charging System Malfunction”
• “Oil Pressure Low”
●If “Low Auxiliary Battery See Owner’s
Manual” is shown
• When the display goes off after several
seconds
*:
Maintain the hybrid system operation for
more than 15 minutes and charge the 12-
volt battery.
• When the display does not go off:
Start up the hybrid system using the proce-
dures for “If the 12-volt battery is dis-
charged” ( P.405)
*: Displays for about 6 seconds
●If “Maintenance required for Traction bat-
tery cooling parts See owner’s manual” is
shown, the filter may be clogged, the air
intake vent may be blocked, or there may
be a gap in the duct. Therefore, perform
the following correction procedure.
• If the air intake vent and filter of the hybrid battery (traction battery) are dirty, per-

4067-2. Steps to take in an emergency
Push the tab in and lift the lid off.
3Open the exclusive jump starting
terminal cover.
4 Remove the engine cover.

4077-2. Steps to take in an emergency
7
When trouble arises
5Connect a positive jumper cable clamp to on your vehicle and connect the
clamp on the other end of the positive cab le to on the second vehicle. Then,
connect a negative cable clamp to on the second vehicle and connect the
clamp at the other end of the negative cable to .
Exclusive jump starting terminal (your vehicle)
Positive (+) battery terminal (second vehicle)
Negative (-) battery terminal (second vehicle)
Solid, stationary, unpainted metallic point away from the exclusive jump starting
terminal and any mo ving parts as shown in the illustration
6 Start the engine of the second vehi-
cle. Increase the engine speed
slightly and maintain at that level for
approximately 5 minutes to
recharge the 12-volt battery of your
vehicle.
7 Open and close any of the doors of
your vehicle with the power switch
OFF.
8 Maintain the engine speed of the
second vehicle and start the hybrid
system of your vehicle by turning
the power switch to ON.
9 Make sure the “READY” indicator
comes on. If the indicator light does not come on, contact your Lexus
dealer.
10 Once the hybrid system has
started, remove the jumper cables
in the exact reverse order from
which they were connected.
11 Close the exclusive jump starting
terminal cover, and reinstall the fuse
box cover to its original position.
Once the hybrid system starts, have
the vehicle inspected at your Lexus
dealer as soon as possible.A
B
C
D
A
B
C
D

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

4117-2. Steps to take in an emergency
7
When trouble arises
and radiator core (radiator) for any
leaks.
Radiator
Cooling fans
If a large amount of coolant leaks, immedi-
ately contact your Lexus dealer.
4The coolant level is satisfactory if it
is between the “FULL” and “LOW”
lines on the reservoir.
Reservoir
“FULL” line
“LOW” line
5 Add coolant if necessary.
Water can be used in an emergency if coolant is unavailable.
6
Start the hybrid system and turn the
air conditioning system on to check
that the radiator cooling fans oper-
ate and to check for coolant leaks
from the radiator or hoses.
The fans operate when the air conditioning
system is turned on immediately after a
cold start. Confirm that the fans are oper-
ating by checking the fan sound and air
flow. If it is difficult to check these, turn the
air conditioning system on and off repeat-
edly.
(The fans may not oper ate in freezing tem-
peratures.)
7 If the fans are not operating:
Stop the hybrid system immediately
and contact your Lexus dealer.
If the fans are operating:
Have the vehicle inspected at the
nearest Lexus dealer.
8 Check if “Engine Coolant Temp
High Stop in a Safe Place See
Owner’s Manual” is shown on the
multi-information display.
If the message does not disappear:
Stop the hybrid system and contact
your Lexus dealer.
If the message is not displayed:
Have the vehicle inspected at the
nearest Lexus dealer.
A
B
A
B
C