2018 LEXUS RX450h cooling

704 8-2. Steps to take in an emergency
RX450h_RX450hL _U_OM48F85U■
If “Hybrid System Overheated Reduced Output Power” is shown on the
multi-information display
Stop the vehicle in a safe place.
Stop the hybrid system an d carefully lift the hood.
After the hybrid system has
cooled down, inspect the hoses
and radiator core (radiator) 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
Add coolant if necessary. Water can be used in an emergency
if coolant is unavailable. 1
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2
4
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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

7159-1. Specifications
9
Vehicle specifications
RX450h_RX450hL _U_OM48F85U* : The coolant capacity is a reference quantity.
If replacement is necessary, contact your Lexus dealer.Cooling system Capacity
* Gasoline
engine 
RX450h
10.7 qt. (10.1 L, 8.9 Imp. qt.) 
RX450hL
13.2 qt. (12.5 L, 11 Imp. qt.)
Power control
unit 2.0 qt. (1.9 L, 1.7 Imp. qt.)
Coolant type Use either of the following:
• “Toyota Super Long Life Coolant”
• Similar high-quality ethylene glycol-based
non-silicate, non-amine, non-nitrite, and non-
borate coolant with long-life hybrid organic
acid technology
Do not use plain water alone.
Ignition system (spark plug) Make DENSO FK20HBR8
Gap 0.03 in. (0.8 mm)
NOTICE ■
Iridium-tipped spark plugs
Use only iridium-tipped spark plugs. Do not adjust the spark plug gap.
Electrical system 12-volt battery
Open voltage at 68 ° F (20 ° C): 12.6 V or higher: Fully charged
12.2 — 12.4 V: Half charged
12.0 V or lower: Discharged
(Voltage is checked 20 minutes after the hybrid
system and all lights are turned off.)
Charging rates 5 A max.

774 Alphabetical index
RX450h_RX450hL _U_OM48F85UChild-protectors.....................................139
Cleaning.......................................580, 584
Aluminum wheels ............................... 581
Exterior................................................... 580
Interior .................................................... 584
Seat belts ............................................... 585
Clock ................................................ 96, 548
Coat hooks.............................................. 559
Compass .................................................. 567
Condenser .............................................. 602
Console box ........................................... 534
Consumption screen ................. 105, 124
Coolant
Capacity .................................................. 715
Checking................................................. 601
Preparing and checking
before winter ................................... 390
Cooling system ...................................... 601
Hybrid system overheating ..........702
Cornering lights .................................... 259
Cruise control
Dynamic radar cruise control
with full-speed range ................... 306
Cup holders ............................................ 535
Curtain shield airbags ........................... 37
Customizable features ....................... 736
Customized mode ............................... 379 Daytime running light system.......... 260
Defogger
Outside rear view mirrors ..............516
Rear window..........................................516
Windshield..............................................516
Differential ................................................ 716
Dimensions ............................................... 710
Dinghy towing ....................................... 238
Display
Dynamic radar cruise control
with full-speed range ...................306
Energy monitor..................................... 124
LKA (Lane-Keeping Assist)......... 302
Multi-information display.................. 101
Warning messages .......................... 667
Do-it-yourself maintenance............. 593
Doors
Automatic door locking and
unlocking system..............................139
Door lock................................................ 138
Outside rear view mirrors ..............193
Power back door ................................ 142
Rear door child-p rotectors ............139
Side doors ...............................................136
Side windows ........................................196 D