Page 386 of 568

3866-3. Do-it-yourself maintenance
PRIUS +_OM_OM47D30E_(EE)
Check the radiator and condenser and clear away any foreign objects.  
If either of the above parts is extremely dirty or you are not sure of 
their condition, have your vehicle inspected by any authorized Toyota 
retailer or Toyota authorized repairer, or any reliable repairer.
WARNING
■ When the hybrid system is hot 
Do not remove the engine/power control unit coolant reservoir caps. 
The cooling system may be under pressure and may spray hot coolant if the 
cap is removed, causing serious injuries, such as burns.
NOTICE
■ When adding coolant 
Coolant is neither plain water nor straight antifreeze. The correct mixture of 
water and antifreeze must be used to provide proper lubrication, corrosion
protection and cooling. Be sure to read the antifreeze or coolant label. 
■ If you spill coolant 
Be sure to wash it off with water to prevent it from damaging parts or paint.
Radiator and condenser
WARNING
■ When the hybrid system is hot 
Do not touch the radiator or condenser as they may be hot and cause seri- 
ous injuries, such as burns. 
■ When the electric cooling fans are operating 
Do not touch the engine compartment. 
With the power switch in ON mode, the electric cooling fans may automati- 
cally start to run if the air conditioning is on and/or the coolant temperature
is high. Be sure the power switch is off when working near the electric cool- 
ing fans or radiator grille. 
     
        
        Page 443 of 568

4437-2. Steps to take in an emergency
PRIUS +_OM_OM47D30E_(EE)
7
When trouble arises
If you think something is wrong
●Fluid leaks under the vehicle 
(Water dripping from the air conditioning after use is normal.) 
● Flat-looking tires or uneven tire wear 
● High coolant temperature warning light flashes or comes on 
● Changes in exhaust sound 
● Excessive tire squeal when cornering 
● Strange noises related to the suspension system 
● Pinging or other noises related to the hybrid system 
● Engine missing, stumbling or running 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 notice any of the following symptoms, your vehicle proba-
bly needs adjustment or repair. Contact any authorized Toyota 
retailer or Toyota authorized repairer, or any reliable repairer as 
soon as possible.
Visible symptoms
Audible symptoms
Operational symptoms 
     
        
        Page 449 of 568

4497-2. Steps to take in an emergency
PRIUS +_OM_OM47D30E_(EE)
7
When trouble arises
(If equipped)
Hybrid system overheat warning light (warning buzzer) 
Indicates that the hybrid system has overheated 
This light may come on when driving under severe operat-
ing conditions, and the output of the hybrid system may 
temporarily decrease in order to protect the system. (For 
example, when driving up a long steep hill or driving up a
steep hill in reverse.) 
 Stop the vehicle in a safe place. 
Handling method ( P. 520)
(If equipped)
Cruise control indicator (yellow indicator) 
Indicates a malfunction in the cruise control 
 Have the vehicle inspected by any authorized Toyota 
retailer or Toyota authorized repairer, or any reliable
repairer immediately.
(Only outer frame  flashes)(If equipped)
Low hybrid battery (traction battery) warning light 
(warning buzzer)
Hybrid battery (traction battery) level becomes low 
because the shift position is in N for long time 
 Because recharging is not possible when the shift 
position is in N, shift the shift position to P when 
parking the vehicle for a long time.
High coolant temperature warning light 
Changes from a flashing to a solid light when the engine
coolant temperature increases 
 Immediately stop the vehicle in a safe place.  
( P. 518)
Automatic headlight leveling system warning light 
Indicates a malfunction in the automatic headlight leveling 
system
 Have the vehicle inspected by any authorized Toyota 
retailer or Toyota authorized repairer, or any reliable 
repairer immediately.
Open door warning light (warning buzzer)*3
Indicates that a door is not fully closed
 Check that all the doors are closed.
Low fuel level warning light 
Indicates that remaining fuel is approximately 6.0 L (1.6 
gal., 1.3 Imp.gal.) or less 
 Refuel the vehicle.
Warning lightWarning light/Details/Actions 
     
        
        Page 518 of 568

5187-2. Steps to take in an emergency
PRIUS +_OM_OM47D30E_(EE)
If your vehicle overheats
■If the high coolant temperature warning light comes on or 
flashes 
Stop the vehicle in a safe place and turn 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 (radiator) for any leaks. 
Radiator 
Cooling fans
If a large amount of coolant 
leaks, immediately contact 
any authorized Toyota retailer 
or Toyota authorized repairer,
or any reliable repairer.
The following may indicate that your vehicle is overheating. 
● The high coolant temperature warning light (P. 449) comes on 
or flashes, or a loss of hybrid system power is experienced. (For 
example, the vehicle speed does not increase.) 
● Vehicles without multi-information display: The hybrid system 
overheat warning light ( P. 449) comes on. 
● Vehicles with multi-information display: The warning message 
indicating overheat is shown on the multi-information display. 
( P. 464) 
● Steam comes out from under the hood.
Correction procedures
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3
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2 
     
        
        Page 519 of 568

5197-2. Steps to take in an emergency
PRIUS +_OM_OM47D30E_(EE)
7
When trouble arises
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 emer- 
gency if coolant is unavailable.
Start the hybrid system and turn the air conditioning system on to 
check that the radiator cooling fans operate and to check for 
coolant leaks from the radiator or hoses.
The fans operate when the air condi tioning system is turned on immedi- 
ately after a cold start. Confirm that the fans are operating by checking 
the fan sound and air flow. If it is difficult to check these, turn the air con-
ditioning system on and off repeatedly. (The fans may not operate in 
freezing temperatures.)
If the fans are not operating: 
Stop the hybrid system immediately and contact any authorized 
Toyota retailer or Toyota authorized repairer, or any reliable 
repairer. 
If the fans are operating: 
Have the vehicle inspected at the nearest any authorized Toyota 
retailer or Toyota authorized repairer, or any reliable repairer.
4
1
2
3
5
6
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        Page 520 of 568
5207-2. Steps to take in an emergency
PRIUS +_OM_OM47D30E_(EE) 
■If the hybrid system overheat warning light comes on or the 
warning message indicating overheat is shown on the multi- 
information display 
Stop the vehicle in a safe place. 
Stop the hybrid system and 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 
any authorized Toyota retailer 
or Toyota authorized repairer,
or any reliable repairer.
The coolant level is satisfactory if it is between the “F” and “L” 
lines on the reservoir. 
Reservoir 
“F” line 
“L” line 
Add coolant if necessary.
Water can be used in an emer- 
gency if coolant is unavailable. 
If water was added in an emer- 
gency, have the vehicle 
inspected at any authorized
Toyota retailer or Toyota autho- 
rized repairer, or any reliable 
repairer as soon as possible.
1
2
3
1
2
4
1
2
3
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        Page 521 of 568

5217-2. Steps to take in an emergency
PRIUS +_OM_OM47D30E_(EE)
7
When trouble arises
After stopping the hybrid system and waiting for 5 minutes or 
more, start the hybrid system and check for the instrument clus- 
ter or multi-information display. 
If the hybrid system overheat warning light does not turn off or 
the message does not disappear:  
Stop the hybrid system and contact any authorized Toyota 
retailer or Toyota authorized repairer, or any reliable repairer. 
If the hybrid system overheat warning light does not come on or 
the message is not displayed:  
The hybrid system temperature has dropped and the vehicle may 
be driven normally.
However, if the warning light comes on again frequently or the message 
appears again frequently, contact any authorized Toyota retailer or 
Toyota authorized repairer, or any reliable repairer.
WARNING
■ 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 hood, 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 indicator on the 
power switch and the “READY” indicator are off.  
When the hybrid system is operating, the gasoline engine may automati- 
cally start, or the cooling 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 reservoir cap while the hybrid system and radia- 
tor are hot. 
High temperature steam or coolant could spray out.
6 
     
        
        Page 522 of 568
5227-2. Steps to take in an emergency
PRIUS +_OM_OM47D30E_(EE)
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 foreign matter (such as sand or dust 
etc.). 
● Do not use any coolant additive.