engine overheat LEXUS RX450h 2018 Owners Manual

TABLE OF CONTENTS
6
RX450h_RX450hL _U_OM48F85U7-1. Maintenance and care
Cleaning and protecting
the vehicle exterior ................580
Cleaning and protecting
the vehicle interior.................. 584
7-2. Maintenance
Maintenance
requirements ............................ 587
General mainte nance..............589
Emission inspection and
maintenance (I/M)
programs.................................... 592
7-3. Do-it-yourself
maintenance
Do-it-yourself service
precautions................................ 593
Hood ............................................... 595
Positioning a floor jack ............ 596
Engine compartment ............... 597
12-volt battery ............................. 605
Tires .................................................... 611
Tire inflation pressure .............. 620
Wheels ........................................... 623
Air conditioning filter ............... 625
Windshield wiper inserts ........ 628
Electronic key battery.............. 630
Checking and replacing
fuses.............................................. 632
Headlight aim .............................. 635
Light bulbs .................................... 637 8-1. Essential information
Emergency flashers .................. 652
If your vehicle has
to be stopped in
an emergency .......................... 653
8-2. Steps to take in
an emergency
If your vehicle needs to be
towed ........................................... 654
If you think something is
wrong........................................... 659
If a warning light turns
on or a warning buzzer
sounds ......................................... 660
If a warning message is
displayed .................................... 667
If you have a flat tire .................. 673
If the hybrid system will
not start ....................................... 690
If the electronic key does
not operate properly ............. 692
If the 12-volt battery is
discharged................................. 695
If your vehicle overheats......... 702
If the vehicle becomes stuck .........7067
Maintenance and care 8
When trouble arises

17Pictorial index
RX450h_RX450hL _U_OM48F85UWindshield wipers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 267 Precautions against winter season . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 390
To prevent freezing (windshield wiper de-icer)
* . . . . . . . . . . . . . . . . . . . . . . . . P. 516
Precautions against car wash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 582
Fuel filler door . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P . 274Refueling method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 276
Fuel type/fuel tank capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 712
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 611Tire size/inflation pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 717
Winter tires/tire chain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 39 0
Checking/rotation/tire pressure warning system . . . . . . . . . . . . . . . . . . . . . . . . P. 611
Coping with flat tires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 673
Hood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .P. 595Opening. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 595
Engine oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 713
Coping with overheat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 702
Headlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 258
Turn signal lights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .P. 2 52
Parking lights/daytime running lights. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 258
Front side marker lights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 258
Fog lights. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 266
Cornering lights
* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .P. 259
Stop/tail lights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 258
License plate lights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 258
Back-up lights Shifting the shift lever to R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 246
Rear side marker lights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 258 4
5
6
7
Light bulbs of the exte rior lights for driving
(Replacing method: P. 637, Watts: P. 719)
* : If equipped8
9
10
11
12
13
14
15
16
17

100 2. Instrument cluster
RX450h_RX450hL _U_OM48F85U■
Tachometer
Hybrid System Indicator switches to the tachometer when driving mode is in sport mode.
The settings of the tachometer display can be changed on of the multi-information
display. ( → P. 108)■
Engine speed
On hybrid vehicles, engine speed is precisel y controlled in order to help improve fuel
efficiency and reduce exhaust emissions etc.
There are times when the engine speed that is displayed may differ even when vehicle
operation and driving conditions are the same. ■
Brightness of the meters (d ay mode and night mode)
The brightness of the meters is changed between day mode and night mode. ●
Day mode: When the tail lights are off or when the tail lights are on but the surrounding
area is bright ●
Night mode: When the tail lights are on and the surrounding area is dark ■
Outside temperature display ●
In the following situations, the correct outside temperature may not be displayed, 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 sy stem may be malfunctioning.
Take your vehicle to your Lexus dealer. ■
Clock settings screen (vehicles with a navigation system only)
If the clock adjustment screen is displayed continuously wh en attempting to change the
clock settings, the system may be malfunctioning.
Have the vehicle inspected by your Lexus dealer. ■
Customization
Some functions can be customized. ( → P. 108)
NOTICE ■
To prevent damage to the engine and its components●
Do not let the indicator needle of the tachometer enter the red zone, which indicates
the maximum engine speed. ●
The engine may be overheating if the engine coolant temperature gauge is in the red
zone (H). In this case, immediately stop the vehicle in a safe place, and check the
engine after it has cooled completely. ( → P. 702)

2154-1. Before driving
4
Driving
RX450h_RX450hL _U_OM48F85UWARNING
Observe the following precautions.
Failure to do so may result in death or serious injury. ■
When driving the vehicle ●
During normal driving, do not turn off the hybrid system. Turning the hybrid system off
while driving will not cause loss of steering or braking control, however, power assist
to the steering will be lost. This will make it more difficult to steer smoothly, so you
should pull over and stop the vehicle as soon as it is safe to do so.
In the event of an emergency, such as if it becomes impossible to stop the vehicle in
the normal way: → P. 653●
Use engine braking (downshift) to maintain a safe speed when driving down a steep
hill.
Using the brakes continuously may cause th e brakes to overheat and lose effective-
ness. ( → P. 246)●
Do not adjust the positions of the steering wheel, the seat, or the inside or outside rear
view mirrors while driving.
Doing so may result in a loss of vehicle control. ●
Always check that all passengers’ arms, he ads or other parts of their body are not
outside the vehicle. ●
Do not drive the vehicle off-road.
This is not an AWD vehicle designed for of f-road driving. Proceed with all due cau-
tion if it becomes unavoidable to drive off-road. ●
Do not drive across a river or through other bodies of water.
This may cause electric/electronic componen ts to short circuit, damage the hybrid
system or cause other serious damage to the vehicle. ●
Do not drive in excess of the speed limit. Even if the legal speed limit permits it, do not
drive over 85 mph (140 km/h) unless your vehicle has high-speed capability tires.
Driving over 85 mph (140 km/h ) may result in tire failure , loss of control and possible
injury. Be sure to consult a tire dealer to determine whether the tires on your vehicle
are high-speed capability tires or no t before driving at such speeds.

2174-1. Before driving
4
Driving
RX450h_RX450hL _U_OM48F85UWARNING
Observe the following precautions.
Failure to do so may result in death or serious injury. ■
If you hear a squealing or scraping noise (brake pad wear limit indicators)
Have the brake pads checked and replaced by your Lexus dealer as soon as possible.
Rotor damage may result if the pads are not replaced when needed.
It is dangerous to drive the vehicle when the wear limits of the brake pads and/or those
of the brake discs are exceeded. ■
When the vehicle is stopped ●
Do not depress the accelerator pedal unnecessarily.
If the shift lever is in any position other than P or N, the vehicle may accelerate sud-
denly and unexpectedly, causing an accident. ●
In order to prevent accidents due to the ve hicle rolling away, always keep depressing
the brake pedal while stopped with the “REA DY” indicator is illuminated, and apply
the parking brake as necessary. ●
If the vehicle is stopped on an incline, in order to prevent accidents caused by the
vehicle rolling forward or backward, alwa ys depress the brake pedal and securely
apply the parking brake as needed. ●
Avoid revving or r acing the engine.
Running the engine at high speed while the vehicle is stopped may cause the exhaust
system to overheat, which could result in a fire if combustible material is nearby.■
When the vehicle is parked ●
Do not leave glasses, cigarette lighters, sp ray cans, or soft drink cans in the vehicle
when it is in the sun.
Doing so may result in the following:
• Gas may leak from a cigarette lighter or spray can, and may lead to a fire.
• The temperature inside the vehicle may cau se the plastic lenses and plastic mate-
rial of glasses to deform or crack.
• Soft drink cans may fracture, causing the contents to spray over the interior of the
vehicle, and may also cause a short circui t in the vehicle’s electrical components.●
Do not leave cigarette lighters in the vehicle. If a cigarette lighter is in a place such as
the glove box or on the floor, it may be lit accidentally when luggage is loaded or the
seat is adjusted, causing a fire. ●
Do not attach adhesive discs to the windsh ield or windows. Do not place containers
such as air fresheners on th e instrument panel or dashbo ard. Adhesive discs or con-
tainers may act as lenses, ca using a fire in the vehicle.●
Do not leave a door or window open if th e curved glass is coated with a metallized
film such as a silver-colored one. Reflecte d sunlight may cause the glass to act as a
lens, causing a fire. ●
Always apply the parking brake, shift the shif t lever to P, stop the hybrid system and
lock the vehicle.
Do not leave the vehicle unattended whil e the “READY” indicator is illuminated.
If the vehicle is parked with the shift leve r in P but the parking brake is not set, the
vehicle may start to move, possibly leading to an accident. ●
Do not touch the exhaust pipes while the “R EADY” indicator is illuminated or imme-
diately after turning the hybrid system off.
Doing so may cause burns.

232 4-1. Before driving
RX450h_RX450hL _U_OM48F85U●
To maintain engine braking efficien cy and charging system performance
when using engine braking, do no t put the transmission in D. ( → P. 246)●
Instability happens more fr equently when descending steep or long downhill
grades. Before descending, slow down and downshift. Do not make sudden
downshifts while descending st eep or long downhill grades.●
Avoid holding the brake pedal down too long or applying the brakes too fre-
quently. This could cause the brakes to overheat and result in reduced braking
efficiency. ●
Due to the added load of the trailer, yo ur vehicle’s engine may overheat on hot
days (at temperatures over 85 ° F [30 ° C]) when driving up a long or steep
grade. If the engine coolant temperat ure gauge indicates overheating, imme-
diately turn off the air conditioning (if in use), pull your vehicle off the road and
stop in a safe spot. ( → P. 702)●
Always place wheel blocks under both the vehicle’s and the trailer’s wheels
when parking. Put the transmission in P and apply the parking brake. Avoid
parking on a slope, but if unavoidable, do so only after performing the follow-
ing:
Apply the brakes and keep them applied.
Have someone place wheel blocks under both the vehicle’s and trailer’s
wheels.
When the wheel blocks are in place, release the brakes slowly until the
blocks absorb the load.
Shift into P and apply the parking brake.
Turn off the hybrid system.●
When restarting afte r parking on a slope:
With the transmission in P, start the hybrid system. Be sure to keep the
brake pedal depressed.
Shift into a forward gear. If reversing, shift into R.
If the parking brake is in manual mode, release the parking brake.
( → P. 254)
Release the brake pedal, and slowly pull or back away from the wheel
blocks. Stop and apply the brakes.
Have someone retrieve the blocks. 1
2
3
4
5
1
2
3
4
5

386 4-5. Using the driving support systems
RX450h_RX450hL _U_OM48F85U■
ECB operating sound
ECB operating sound may be heard in the followi ng cases, but it does not indicate that a
malfunction has occurred. ●
Operating sound heard from the engine compartment when the brake pedal is oper-
ated. ●
Motor sound of the brake system heard from the front part of the vehicle when the
driver’s door is opened. ●
Operating sound heard from the engine compartment when one or two minutes
passed after the stop of the hybrid system. ■
EPS operation sound
When the steering wheel is operated, a motor sound (whirring sound) may be heard.
This does not indicate a malfunction. ■
Automatic reactivation of TRAC, Tr ailer Sway Control and VSC systems
After turning the TRAC, Trailer Sway Contro l and VSC systems off, the systems will be
automatically re-enabled in the following situations: ●
When the power switch is turned off ●
If only the TRAC system is turned off, the TRAC will turn on when vehicle speed
increases
If both the TRAC and VSC systems are turned off, au tomatic re-enabling will not
occur when vehicle speed increases. ■
Reduced effectiveness of the EPS system
The effectiveness of the EPS system is reduced to prevent the system from overheating
when there is frequent steering input over an extended period of time. The steering
wheel may feel heavy as a result . Should this occur, refrain from excessive steering input
or stop the vehicle and turn the hybrid system off. The EPS system should return to nor-
mal within 10 minutes.
WARNING ■
The ABS does not operate effectively when ●
The limits of tire gripping performance have been exceeded (such as excessively
worn tires on a snow covered road). ●
The vehicle hydroplanes while driving at high speed on wet or slick roads.■
Stopping distance when the ABS is operating may exceed that of normal conditions
The ABS is not designed to shorten the vehi cle’s stopping distance . Always maintain a
safe distance from the vehicle in front of you, especially in the following situations: ●
When driving on dirt, grav el or snow-covered roads●
When driving with tire chains ●
When driving over bumps on the road ●
When driving over roads with potholes or uneven surfaces■
TRAC/VSC may not operate effectively when
Directional control an d power may not be achievable wh ile driving on slippery road
surfaces, even if the TRAC/VSC system is op erating. Drive the vehi cle carefully in con-
ditions where stability and power may be lost.

670 8-2. Steps to take in an emergency
RX450h_RX450hL _U_OM48F85U■
If “Shift Is in N Release Accele rator Before Shifting” is shown
Message is displayed when the accele rator pedal has been depressed and
the shift lever is in N. Release the accelerator pedal and shift the shift lever to
D or R. ■
If “Depress Brake when Vehicle Is Stopped Hybrid System May Overheat”
is shown
Message is displayed when the accelerato r pedal is depressed to maintain the
vehicle position when stopped on a upward slope, etc.
If this continues, the hybrid system may overheat.
Release the accelerator pedal and depress the brake pedal. ■
If “Power Turned Off to Save Battery” is displayed
This message is displayed when the power was cut off due to the automatic
power off function.
The next time the hybrid system is star ted, increase the engine speed slightly
and maintain it at that speed for appr oximately 5 minutes to recharge the 12-
volt battery. ■
If “A New Key has been Registered Contact Your Dealer for Details” is dis-
played
This message will be displayed each time the driver's door is opened when the
doors are unlocked from the outside fo r approximately one week after a new
electronic key has been registered.
If this message is displayed but you ha ve not had a new electronic key regis-
tered, ask your Lexus dealer to check if an unknown electronic key (other than
those in your possession) has been registered. ■
When “Headlight System Malfunctio n Visit Your Dealer” is displayed
The following systems may be malfunct ioning. Have the vehicle inspected by
your Lexus dealer immediately. ●
The LED headlight system ●
The automatic headlight leveling system ●
Automatic High Beam ●
AFS (Adaptive Front-lighting System) (if equipped)

702 8-2. Steps to take in an emergency
RX450h_RX450hL _U_OM48F85U■
“Engine Coolant Temp High Stop in a Safe Place See Owner’s Manual” is
shown on the multi-information display
Stop the vehicle in a safe place and tu rn off the air conditioning system, and
then stop the hybrid system.
If you see steam: Carefully lift the hood after the steam subsides.
If you do not see steam: Carefully lift the hood.
After the hybrid system has
cooled down sufficiently, inspect
the hoses and radiator core (radi-
ator) for any leaks.
Radiator
Cooling fans If a large amount of coolant leaks,
immediately contact your Lexus
dealer.
The coolant level is satisfactory if
it is between the “FULL” and
“LOW” lines on the reservoir.
Reservoir
“FULL” line
“LOW” line
Radiator capIf your vehicle overheats The following may indicate that your vehicle is overheating. ●
The needle of the engine coolant temperature gauge ( → P. 96) enters the
red zone, or a loss of hybrid system 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 Overheated Reduced Output Power” is shown on the
multi-information display. ●
Steam comes out from under the hood.
Correction procedures 1
2
3
1
2
4
1
2
3
4

7058-2. Steps to take in an emergency
8
When trouble arises
RX450h_RX450hL _U_OM48F85UStart the hybrid system and check if “Hybrid System Overheated Reduced
Output Power” 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. WARNING ■
To prevent an accident or injury when inspecting under the hood of your vehicle
Observe the following precautions.
Failure to do so may result in serious injury such as burns.●
If steam is seen coming from under the h ood, do not open the hood until the steam
has subsided. The engine compartment may be very hot. ●
After the hybrid system has been turned off, check that the “READY” indicator is off.
When the hybrid system is operating, the gasoline engine may automatically start, or
the cooling fans may suddenly operate even if the gasoline engine stops. Do not
touch or approach rotating parts such as th e fans, which may lead to fingers or cloth-
ing (especially a tie, a scarf or a muffler) getting caught, resulting in serious injury.●
Do not loosen the radiator cap and the coolant reservoir caps wh ile the hybrid system
and radiator are hot.
High temperature steam or coolant could spray out.
NOTICE ■
When adding engine/power control unit coolant
Add coolant slowly after the hybrid system has cooled down sufficiently. Adding cool
coolant to a hot hybrid system too quickly can cause damage to the hybrid system.■
To prevent damage to the cooling system
Observe the following precautions: ●
Avoid contaminating the coolant with foreig n matter (such as sand or dust etc.).●
Do not use any coolant additive. 6