engine TOYOTA SIENNA HYBRID 2023 Repair Manual

4767-2. Steps to take in an emergency
The warning lights and warning buzzers operate as follows depend-
ing on the content of the message. If a message indicates the need
for inspection by a dealer, have the vehicle inspected by your Toyota
dealer immediately.
*: A buzzer sounds the first time a message is show n on the multi-informa-
tion display.
■Warning messages
The warning messages explained
below may differ from the actual
messages according to operation
conditions and vehicle specifica-
tions.
■Warning buzzer
In some cases, the buzzer may not
be heard due to being in a noisy
location or audio sound.
■If a message that indicates the
need for visiting your Toyota
dealer is displayed
The system or part shown on the
multi-information di splay is malfunc-
tioning. Have the vehicle inspected
by your Toyota dea ler immediately.
■If a message that indicates the
need for referring to Owner’s
Manual is displayed
●If “Engine Coolant Temp High
Stop in a Safe Place See Owner’s
Manual” is shown, follow the
Messages and warnings
Warning lightWarning buzzer*Warning
Sounds
• Indicates an import ant situation, such
as when a system related to driving is
malfunctioning or that danger may
result if the correction procedure is not
performed
• Indicates a situat ion, such as when
damage to the vehicle or danger may
result
Comes on or flashesSounds
Indicates an importan t situation, such as
when the systems shown on the multi-
information display may be malfunction-
ing
Does not sound
• Indicates a condition, such as malfunc- tion of electrical components, their con-
dition, or indicat es the need for
maintenance
• Indicates a situatio n, such as when an
operation has been performed incor-
rectly, or indicates how to perform an
operation correctly

4777-2. Steps to take in an emergency
7
When trouble arises
instructions (P.512).
●If any of the following messages
are shown on the multi-informa-
tion display, it may indicate a mal-
function. Have the vehicle
inspected by your Toyota dealer
immediately.
• “Smart Key System Malfunction”
• “Hybrid System Malfunction”
• “Check Engine”
• “Hybrid Battery System Malfunc-
tion”
• “Accelerator Syst em Malfunction”
●If any of the following messages
are shown on the multi-informa-
tion display, it may indicate a mal-
function. Immediately stop the
vehicle and contact your Toyota
dealer.
•“Braking Power Low”
• “12-Volt Battery Charging System Malfunction”
• “Oil Pressure Low”
●If any of the following messages
are shown on the multi-informa-
tion display, the vehicle may have
run out of fuel. Stop the vehicle in
a safe place and, if the fuel level is
low, refuel the vehicle.
• “Hybrid System Stopped”
• “Engine Stopped”
●If “Low Auxiliary Battery See
Owner’s Manual” is shown
• When the display goes off after
several seconds
*:
Maintain the hybri d system opera-
tion 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
procedures for “If the 12-volt battery
is discharged” ( P.504)
*: Displays for about 6 seconds
●If “Maintenance Required for Trac-
tion Battery Cooling Parts See
Owner’s Manual” is shown, the fil-
ter may be clogged, the air intake
vent may be blocked, or there may
be a gap in the duct. Therefore, perform the follo
wing correction
procedure.
• Cleaning the hybrid battery (trac-
tion battery) air intake vents
(
P.440)
If the warning message is shown
even if the vents are cleaned,
have the vehicle inspected by
your Toyota dealer.
■If “Engine Oil Level Low Add or
Replace” is displayed
The engine oil level may be low.
Check the level o f the engine oil,
and add engine oil if necessary.
This message may be displayed if
the vehicle is stopped on a slope.
Move the vehicle to a level surface
and check if the message disap-
pears.
■If “Hybrid System Stopped
Steering Power Low” is dis-
played
This message is displayed if the
hybrid system is stopped while driv-
ing.
When steering wheel operations are
heavier than usual, grip the steering
wheel firmly and operate it using
more force than usual.
■If “Hybrid System Overheated
Output Power Reduced” is
shown
The message may be shown when
driving under severe operating con-
ditions. (For example, when driving
up a long steep hill or driving up a
steep hill in reverse.)
Coping method: P.512
■If “Traction Battery Needs to be
Protected Refrain from the Use
of N Position” is shown
This message may be displayed
when the shift lever is in N.
As the hybrid battery (traction bat-
tery) can not be charged when the
shift lever is in N, shift the shift lever
to P when the vehicle is stopped.

4797-2. Steps to take in an emergency
7
When trouble arises
the message is resolved. ( P.268,
464)
●PCS (Pre-Collis ion System)
●LTA (Lane Tracing Assist)
●Dynamic radar cruise control with
full-speed range
■If “Maintenance Required
Soon” is shown
Indicates that all maintenance
according to the driven distance on
the maintenance schedule
* should
be performed soon.
Comes on approximately 4500
miles (7200 km) after the message
has been reset.
If necessary, perform maintenance.
Please reset the message after the
maintenance is performed.
(  P.403)
*: Refer to the separate “Scheduled
Maintenance Guide” or “Owner’
Manual Supplement” for the main-
tenance interval applicable to your
vehicle.
■If “Maintenance Required Visit
Your Dealer” is shown
Indicates that all maintenance is
required to correspond to the driven
distance on the maintenance sched-
ule
*.
Comes on approximately 5000
miles (8000 km) after the message
has been reset. (The indicator will
not work properly unless the mes-
sage has been reset.)
Perform the necessary mainte-
nance. Please reset the message
after the maintenance is performed.
(  P.403)
*: Refer to the separate “Scheduled
Maintenance Guide” or “Owner’
Manual Supplement” for the main-
tenance 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
necessary.
After changing the engine oil, make
sure to reset t he message.
(  P.415)
■If “Oil Maintenance Required
Visit Your Dealer” is displayed
Indicates that the engine oil should
be changed.
Check and change the engine oil
and oil filter by yo ur Toyota dealer.
After changing the engine oil, make
sure to reset t he message.
(
P.415)
■Warning buzzer
 P.471
NOTICE
■“High Power Consumption
Power to Climate Temporar-
ily Limited” is frequently
shown
There is a possible malfunction
relating to the charging system or
the 12-volt battery may be deteri-
orating. Have the vehicle
inspected by your Toyota dealer.
■If “Low Auxiliary Battery See
Owner’s Manual” is displayed
frequently
The 12-volt battery may have
deteriorated.
As the battery may discharge in
this state when left unattended,
have the battery inspected by
your Toyota dealer.

4977-2. Steps to take in an emergency
7
When trouble arises
WARNING
●Do not use more than one com-
pact spare tire simultaneously.
●Replace the compact spare tire
with a standard tire as soon as
possible.
●Avoid sudden acceleration,
abrupt steering, sudden brak-
ing and shifting operations that
cause sudden engine braking.
■When the compact spare tire
is attached
The vehicle speed may not be
correctly detecte d, and the follow-
ing systems may not operate cor-
rectly:
• ABS & Brake assist
• VSC/Trailer Sway Control
• TRAC
• Dynamic radar cruise control with full-speed range
• PCS (Pre-Collision System)
• EPS
• LTA (Lane Tracing Assist)
• Tire pressure warning system
• AHB (Automatic High Beam)
• BSM (Blind Spot Monitor) (if equipped)
• Rear view monitor system (if equipped)
• Panoramic view monitor (if equipped)
• Toyota parking assist monitor (if equipped)
• Intuitive parking assist (if equipped)
• PKSB (Parking Support Brake) (if equipped)
• Navigation system (if equipped)
Also, not only c an the following
system not be utilized fully, but it
may actually negatively affect the
drive-train components:
• E-Four (Electronic On-Demand
AWD system) (AWD models)
■Speed limit when using the
compact spare tire
Do not drive at speeds in excess
of 50 mph (80 km /h) when a com-
pact spare tire is installed on the
vehicle.
The compact spare tire is not
designed for driving at high
speeds. Failure to observe this
precaution may lead to an acci-
dent causing death or serious
injury.
■After using the tools and jack
Before driving, ma ke sure all the
tools and jack are securely in
place in their storage location to
reduce the possibility of personal
injury during a collision or sudden
braking.
NOTICE
■Be careful when driving over
bumps with the compact
spare tire installed on the
vehicle
The vehicle height may become
lower when drivi ng with the com-
pact spare tire compared to when
driving with standard tires. Be
careful when driving over uneven
road surfaces.
■Driving with tire chains and
the compact spare tire
Do not fit tire chains to the com-
pact spare tire.
Tire chains may damage the vehi-
cle body and adversely affect driv-
ing performance.

5057-2. Steps to take in an emergency
7
When trouble arises
up the cover.3Open the exclusive jump
starting terminal cover.
4 Connect a positive jumper cable clamp to on your vehicle and
connect the clamp on the other end of the positive cable 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 term inal (second vehicle)
Solid, stationary, unpainted metallic point away from the exclu -
sive jump starting terminal and any moving parts as shown in th e
illustration
5 Start the engine of the sec-
ond vehicle. Increase the
engine speed slightly and maintain at that level for
approximately 5 minutes to
A
B
C
D
A
B
C
D

5067-2. Steps to take in an emergency
recharge the 12-volt battery
of your vehicle.
6 Maintain the engine speed of
the second vehicle and start
the hybrid system of your
vehicle by turning the power
switch to ON.
7 Make sure the “READY” indi-
cator comes on. If the indica-
tor light does not come on,
contact your Toyota dealer.
8 Once the hybrid system has
started, remove the jumper
cables in the exact reverse
order from which they were
connected.
9 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 Toyota dealer as soon as
possible.
■Starting the hybrid system
when the 12-volt battery is dis-
charged
The hybrid system cannot be
started by push-starting.
■To prevent 12-vol t battery dis-
charge
●Turn off the headlights and the
audio system while the hybrid sys-
tem is off.
●Turn off any unnec essary electri-
cal components when the vehicle
is running at a low speed for an
extended period, such as in heavy
traffic.
■When the 12-volt battery is
removed or discharged
●Information stored in the ECU is
cleared. When the 12-volt battery
is depleted, have the vehicle
inspected at you r Toyota dealer.
●Some systems may require initial-
ization. (P.551)
■When removing the 12-volt bat-
tery terminals
When the 12-volt battery terminals
are removed, the information stored
in the ECU is cleared. Before
removing the 12- volt battery termi-
nals, contact your Toyota dealer.
■Charging the 12-volt battery
The electricity stored in the 12-volt
battery will discha rge gradually even
when the vehicle i s not in use, due
to natural dischar ge and the drain-
ing effects of certain electrical appli-
ances. If the vehicle is left for a long
time, the 12-volt battery may dis-
charge, and the hybrid system may
be unable to start. (The 12-volt bat-
tery recharges automatically while
the hybrid system is operating.)
■When recharging or replacing
the 12-volt battery
●In some cases, it may not be pos-
sible to unlock the doors using the
smart key system when the 12-
volt battery is discharged. Use the
wireless remote c ontrol or the
mechanical key to lock or unlock
the doors.
●The hybrid syste m may not start
on the first attemp t after reinstall-
ing the 12-volt battery. In that
case, start the hybrid system in
the same manner as when the
electronic key does not operate
properly ( P.503). This is not a
malfunction, as the hybrid system
will start normally on the second
attempt.
●The power switch mode is memo-
rized by the vehicle. When the 12-
volt battery is reconnected, the
system will return to the mode it

5097-2. Steps to take in an emergency
7
When trouble arises
■If the engine coolant tem-
perature gauge enters the
red zone or “Engine Cool-
ant 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 con-
ditioning 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 and radia-
tor core (radiator) for any
leaks.
Radiator
Cooling fan
If a large amount of coolant leaks,
immediately contact your Toyota
dealer.
4The coolant level is satisfac-
tory if it is between the
“FULL” and “LOW” lines on
the reservoir.
Reservoir
“FULL” line
If your vehicle over-
heats
The following may indicate
that your vehicle is over-
heating.
The needle of the engine
coolant temperature gauge
( P.97, 101) enters the red
zone, or a loss of hybrid
system power is experi-
enced. (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 Output
Power Reduced” is shown
on the multi-information dis-
play.
Steam comes out from
under the hood.
Correction procedures
A
B
A
B

5107-2. Steps to take in an emergency
“LOW” line
5 Add coolant if necessary.
Water can be us ed in an emer-
gency if engine coolant is unavail-
able.
6 Start the hybrid system and
turn the air conditioning sys-
tem on to check that the radi-
ator cooling fan operates and
to check for coolant leaks
from the radiator or hoses.
The fan operates when the air con-
ditioning system is turned on imme-
diately after a cold start. Confirm
that the fan is op erating by check-
ing the fan sound and air flow. If it is
difficult to check th ese, turn the air
conditioning system on and off
repeatedly. (The f an may not oper-
ate in freezing temperatures.)
7 If the fan is not operating:
Stop the hybrid system
immediately and contact your
Toyota dealer.
If the fan is operating:
Have the vehicle inspected at
the nearest Toyota dealer.
8 Check if “Engine Coolant
Temp High Stop in a Safe
Place See Owner’s Manual”
is shown on the multi-infor-
mation display.
If the message does not disappear:
Stop the hybrid system and contact
your Toyota dealer.
If the message is not displayed:
Have the vehicle inspected at the
nearest Toyota dealer.
■If “Hybrid System Over-
heated Output Power
Reduced” is shown on the
multi-information display
1 Stop the vehicle in a safe
place.
2 Stop the hybrid system and
carefully lift the hood.
3 After the hybrid system has
cooled down, inspect the
hoses and radiator core (radi-
ator) for any leaks.
Radiator
Cooling fan
If a large amount of coolant leaks,
immediately contact your Toyota
dealer.
4The coolant level is satisfac-
tory if it is between the
C
A
B

5117-2. Steps to take in an emergency
7
When trouble arises
“FULL” and “LOW” lines on
the reservoir.
Reservoir
“FULL” line
“LOW” line
5 Add coolant if necessary.
Water can be used in an emer-
gency if power control unit coolant
is unavailable.
6After stopping the hybrid sys-
tem and waiting for 5 minutes
or more, start the hybrid sys-
tem again and check for the
multi-information display.
If the message does not disappear:
Stop the hybrid system and contact
your Toyota dealer.
If the message is not displayed:
The hybrid system temperature has
dropped and the vehicle may be
driven normally.
However, if the message appears
again frequently, contact your Toyota dealer.
A
B
C
WARNING
■When inspecting under the
hood of your vehicle
Observe the following precau-
tions.
Failure to do so may result in seri-
ous injury such as burns.
●If steam is seen coming from
under the hood, do not open the
hood until the steam has sub-
sided. The engine compart-
ment may be very hot.
●After the hybrid system has
been turned off , check that the
“READY” indicator is off.
When the hybrid system is oper-
ating, the gasoline engine may
automatically start, or the cool-
ing fan may suddenly operate
even if the gasoline engine
stops. Do not touch or approach
rotating parts such as the fan,
which may lead to fingers or
clothing (especially a tie, a scarf
or a muffler) getting caught,
resulting in serious injury.
●Do not loosen the coolant reser-
voir cap while 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.

5188-1. Specifications
■Engine number
The engine number is stamped on the engine block as shown.
Front
Engine
Model2.5 L 4-cylinder (A25A-FXS)
Type4-cylinder in line
, 4-cycle, gasoline
Bore and stroke3.44  4.07 in. (87.5  103.4 mm)
Displacement151.8 cu. in. (2487 cm3)
Valve clearanceAutomatic adjustment
Fuel
Fuel typeUnleaded gasoline only
Octane Rating87 (Research Octane Number 91) or
higher
Fuel tank capacity (Reference)18 gal. (68.2 L, 15 Imp.gal.)
Electric motor (traction motor)
TypePermanent magnet synchronous motor
Maximum output134 kW
Maximum torque199 ft•lbf (270 N•m, 27.5 kgf•m)