2005 TOYOTA AVENSIS Circuit

A66651A±A SectionAir Solid Electrolyte
(Zirconia Element)
Platinum ElectrodeHeater
Exhaust Gas
CoverIdeal Air±Fuel Mixture
Output Voltage
Richer ± Air Fuel Ratio ± Leaner Element
AA
± DIAGNOSTICSSFI SYSTEM (1ZZ±FE/3ZZ±FE)
05±45
AVENSIS REPAIR MANUAL (RM1018E)
DTC P0125 INSUFFICIENT COOLANT TEMP. FOR
CLOSED LOOP FUEL CONTROL
CIRCUIT DESCRIPTION
The heated oxygen sensor is the planar type. Compared to the conventional type, the sensor element and
the heater portions have a narrower overall. The heater can directly conduct its heat to the zirconia element
via the alumina, it helps to accerate the sensor activation.
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three ± way
catalytic converter is used. For the most efficient use of the three ± way catalytic converter, the air ± fuel ratio
must be precisely controlled so that it is always close to the stoichiometric air ± fuel ratio.
The heated oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity
of the stoichiometric air±fuel ratio. This is used to detect the oxygen concentration in the exhaust gas and
provide the ECM with feedback control the air±fuel ratio.
When the air±fuel ratio becomes LEAN, the oxygen concentration in the exhaust gas increases. And the
heated oxygen sensor informs the ECM of the LEAN condition (low voltage, i. e. less than 0.45 V ).
When the air±fuel ratio is RICHER than the stoichiometric air±fuel ratio, the oxygen concentration in the ex-
haust gas is reduced. And the heated oxygen sensor informs the ECM of the RICH condition (high voltage,
i. e. more than 0.45V). The ECM judges by the voltage output from the heated oxygen sensor whether the
air±fuel ratio is RICH or LEAN and controls the injection time accordingly. If the malfunction of the heated
oxygen sensor causes an output of abnomal voltage, the ECM becomes unable to perform accurate air±fuel
ratio control.
The heated oxygen sensors include a heater which heats the zirconia element. The heater is controlled by
the ECM. When the intake air volume is low (the temperature of the exhaust gas is low), current flows to the
heater in order to heat the sensor for the accurate oxygen concentration detection.
DTC NoDTC Detecting ConditionTrouble Area
P0125
After engine is warmed up, heated oxygen sensor output* does
not change when conditions (a), (b), (c) and (d) continue for at
least 1.5 min:
*: Output value changes at inside of the ECM only
(a) Engine speed: 1,400 rpm or more
(b) Vehicle speed: 40 to 100 km/h (25 to 62 mph)
(c) Throttle valve is not fully closed
(d) 180 sec. or more after starting engine
Open or short in heated oxygen sensor circuit

Heated oxygen sensor

Air induction system

Fuel pressure

Injector

Gas leakage in exhaust system

ECM
05C69±01

+25 %
±12.5 %
More than 0.55 V
Less than 0.4V
Case 1
Case 2
Case 3
Case 4
Output voltage of heated oxygen
sensor (sensor 1: front sensor)
Injection volume
Output voltage
Output voltage of heated oxygen
sensor (sensor 2: rear sensor)Mainly suspect
trouble area
OK
+25 %
±12.5 %
More than 0.55 V
Less than 0.4V
Injection volume
Output voltage
+25 %
±12.5 %
More than 0.55 V
Less than 0.4V
Injection volume
Output voltage
Sensor 1: front sensor
(sensor 1, heater, sensor 1
circuit)
+25 %
±12.5 %
More than 0.55 V
Less than 0.4V
Injection volume
Output voltage
+25 %
±12.5 %
Injection volume
Output voltage
NG
+25 %
±12.5 %
Injection volume
Output voltage
NG
+25 %
±12.5 %
Injection volume
Output voltage
NG
+25 %
±12.5 %
Injection volume
Output voltage
NGExtremely rich or lean of the
actual air±fuel ratio
(Injector, fuel pressure, gas
leakage in exhaust system,
etc.) OK
OK
OK
No reaction
No reaction
No reaction No reaction

Sensor 2: rear sensor
(sensor 2, heater, sensor 2
circuit)
± DIAGNOSTICSSFI SYSTEM (1ZZ±FE/3ZZ±FE)
05±47
AVENSIS REPAIR MANUAL (RM1018E)
INSPECTION PROCEDURE
HINT:
Hand±held tester only:
Narrowing down the trouble area is possible by performing ACTIVE TEST of the following ºA/F CONTROLº
(heated oxygen sensor or other trouble areas can be distinguished).
(a) Perform ACTIVE TEST by the hand±held tester (A/F CONTROL).
HINT:
ºA/F CONTROLº is an ACTIVE TEST which changes the injection volume ±12.5 % or +25 %.
(1) Connect the hand±held tester to the DLC3 on the vehicle.
(2) Turn the ignition switch ON.
(3) Warm up the engine with the engine speed at 2,500 rpm for approximately 90 sec.
(4) Select the item ºDIAGNOSIS / OBD/MOBD / ACTIVE TEST / A/F CONTROLº.
(5) Perform ºA/F CONTROLº with the engine in an idle condition (press the right or left button).
Result:
Heated oxygen sensor reacts in accordance with increase and decrease of injection volume:
+25 %
rich output: More than 0.55 V
±12.5 %
lean output: Less than 0.4 V
NOTICE:
There is a few second delay in the sensor 1 (front sensor) output, and there is about 20 seconds delay
in the sensor 2 (rear sensor)output.

A58684
ECM
5V
VC
VTA
E2 Throttle Position
Sensor
± DIAGNOSTICSSFI SYSTEM (1ZZ±FE/3ZZ±FE)
05±39
AVENSIS REPAIR MANUAL (RM1018E)
DTC P0120 THROTTLE PEDAL POSITION
SENSOR/SWITCH ºAº CIRCUIT
MALFUNCTION
CIRCUIT DESCRIPTION
The throttle position sensor is mounted in the throttle body and
detects the throttle valve opening angle.
When the throttle valve is fully closed, a voltage of approximate-
ly 0.7 V is applied to terminal VTA of the ECM. The voltage ap-
plied to terminal VTA of the ECM increases in proportion to the
opening angle of the throttle valve and becomes approximately
3.5 to 5.0 V when the throttle valve is fully opened. The ECM
judges the vehicle driving conditions from these signals input
from terminal VTA, uses them as one of the conditions for decid-
ing the air±fuel ratio correction, power increase correction and
fuel±cut control etc.
DTC No.DTC Detecting ConditionTrouble Area
P0120
Condition (a) or (b) continues for more than 5 sec.
(a) VTA is less than 0.1 V
(b) VTA is greater than 4.9 V
Open or short in throttle position sensor circuit

Throttle position sensor

ECM
HINT:
After confirming DTC ºP0120º, use the hand±held tester to confirm the throttle valve opening percentage.
Throttle valve opening position expressed as percentageTrouble AreaThrottle valve fully closedThrottle valve fully openTrouble Area
0 %0 %VC circuit open
VTA circuit open or short
Approx. 100 %Approx. 100 %E2 circuit open
05B3S±02

05±38
±
DIAGNOSTICS SFI SYSTEM(1ZZ±FE/3ZZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
DTCP0116ENGINE COOLANT TEMPERATURE CIRCUIT RANGE/PERFORMANCE PROBLEM
CIRCUIT DESCRIPTION
Rfer to DTC P0115 on page 05±34
DTC No.DTC Detecting ConditionTrouble Area
P0116
When the temperature of engine coolant is ±7 C (20 F) with
a cold engine, and if the engine coolant temperature sensor

Engine coolant temperature sensorP0116g,g
value is 20 C (68 F) or less even if it has been 20 min or
more since the engine was warmed up. (2 trip detection logic)
g

Thermostat
INSPECTION PROCEDURE
HINT:

Read freeze frame data using \f \b\f\f
 Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, it is useful for d\
etermining whether the vehicle
was running or stopped, the engine was warmed up or not, the air±fuel ra\
tio was lean or rich, etc. at
the time of the malfunction.

If different DTCs that are related to a different systems are output simultaneously while terminal E2
is used as a ground terminal, terminal E2 may be open.
1READ OUTPUT DTC(BESIDES P0116)
(a)Read the DTC using the hand±held tester.
Result:
Display (DTC output)Proceed to
Only ºP0116º is outputA
ºP0116º and other DTCs are outputB
HINT:
If any other codes besides ºP0116º are output, perform the troubleshooting for those DTCs first.
BGO TO RELEVANT DTC CHART
A
2INSPECT THERMOSTAT (See Page 16±3)
NG REPLACE THERMOSTAT
OK
REPLACE ENGINE COOLANT TEMPERATURE SENSOR
05B3R±02

A72925
E2
Engine Coolant Temperature Sensor
2
1B±W
BR
E2 THWECM
19
E13
E13 285V
R 05±34
± DIAGNOSTICSSFI SYSTEM (1ZZ±FE/3ZZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
DTC P0115 ENGINE COOLANT TEMPERATURE CIRCUIT
CIRCUIT DESCRIPTION
A thermistor is built into the engine coolant temperature sensor and changes the resistance value according
to the engine coolant temperature.
The structure of the sensor and connection to the ECM is the same as the ones of the intake air temperature
sensor.
DTC No.DTC Detecting ConditionTrouble Area
P0115Open or short in water temp. sensor circuit

Open or short in Engine coolant temperature sensor circuit

Engine coolant temperature sensor

ECM
If the ECM detects the DTC ºP0115º, it enters the fail±safe mode in which the engine coolant temperature
is assumed to be 80 C (176 F).
HINT:
After confirming DTC P0115, use the hand±held tester to confirm the engine coolant temperature in ºDIAG-
NOSIS / OBD/MOBD / DATA LIST / ALLº.
Temperature DisplayedMalfunction
±40 C (±40 F)Open circuit
140 C (284 F) or moreShort circuit
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

Read freeze frame data using    
 Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle
was running or stopped, the engine was warmed up or not, the air±fuel ratio was lean or rich, etc. at
the time of the malfunction.

If different DTCs that are related to a different system are output simultaneously while terminal E2 is
used as a ground terminal, terminal E2 may be open.
05B3Q±02

A75743
ECM
Engine Coolant
Temperature Sensor
A76786
Wire Harness Side
E2
Engine Coolant Temperature
Sensor Connector
±
DIAGNOSTICS SFI SYSTEM(1ZZ±FE/3ZZ±FE)
05±35
AVENSIS REPAIR MANUAL (RM1018E)
1READ VALUE OF HAND±HELD TESTER(WATER TEMPERATURE)
(a)Connect the hand±held tester to the DLC3.
(b)Turn the ignition switch ON.
(c)Select the item ºDIAGNOSIS / OBD/MOBD / DATA LIST / ALL / COOLANT TEMPº and read its value
displayed on the hand±held tester.
Temperature: Same as actual engine coolant temperature
Result:
Temperature DisplayedProceed to
±40 C (±40 F)A
140 C (284 F) or moreB
OK (Same as present temperature)C
HINT:

If there is an open circuit, the hand±held tester indicates ±40
C (±40
F).

If there is a short circuit, the hand±held tester indicates 140
C (284
F) or more.
BGo to step 4
CCHECK FOR INTERMITTENT PROBLEMS (See Page 05±5)
A
2 READ VALUE OF HAND±HELD TESTER(CHECK FOR OPEN IN HARNESS)
(a) Disconnect the engine coolant temperature sensor con- nector.
(b) Connect terminals 1 and 2 of the engine coolant tempera- ture sensor connector.
(c) Turn the ignition switch ON.
(d) Select the item ºDIAGNOSIS / OBD/MOBD / DATA LIST / ALL / COOLANT TEMPº and read its value displayed on
the hand±held tester.
Temperature: 140
C (284
F) or more
OK CONFIRM GOOD CONNECTION AT SENSOR. IF OK, REPLACE ENGINE COOLANT TEMP.
SENSOR
NG

(fig. 1)
Acceptable
Resistance k

± 20 0 20 40 60 80 100
(± 4) 32 68 104 140 176 212 30
20
10
5
3
2
1
0.5
0.3
0.2
0.1
Temp.
C (
F)
(fig. 1)
Acceptable
Resistance k

± 20 0 20 40 60 80 100
(± 4) 32 68 104 140 176 212 30
20
10
5
3
2
1
0.5
0.3
0.2
0.1
Temp.
C (
F)
FI4741
05±30
± DIAGNOSTICSSFI SYSTEM (1ZZ±FE/3ZZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
DTC P0110 INTAKE AIR TEMPERATURE CIRCUIT
CIRCUIT DESCRIPTION
The intake air temperature sensor is built into the mass air flow
meter and senses the intake air temperature.
A thermistor built in the sensor changes the resistance value
according to the intake air temperature.
The lower the intake air temperature, the greater the thermistor
resistance value, and the higher the intake air temperature, the
lower the thermistor resistance value (See fig. 1).
The intake air temperature sensor is connected to the ECM
(See below ). The 5 V power source voltage in the ECM is ap-
plied to the intake air temperature sensor from the terminal THA
via resistor R.
That is, the resistor R and the intake air temperature sensor are
connected in series. When the resistance value of the intake air
temperature sensor changes in accordance with changes in the
intake air temperature, the potential at terminal THA also
changes. Based on this signal, the ECM increases the fuel in-
jection volume to improve driveability during cold engine opera-
tion.
DTC No.DTC Detecting ConditionTrouble Area
P0110Open or short in intake air temp. sensor circuit

Open or short in intake air temp. sensor circuit

Intake air temp. sensor (built into mass air flow meter)

ECM
If the ECM detects the DTC ºP0110º, it enters the fail±safe mode in which the intake air temperature is as-
sumed to be 20 C (68 F).
HINT:
After confirming DTC ºP0110º, use the hand±held tester to confirm the intake air temperature from the
ºDIAGNOSIS / OBD/MOBD / DATA LIST / ALLº.
Temperature DisplayedMalfunction
±40 C (±40 F)Open circuit
140 C (284 F) or moreShort circuit
05B3P±02

A72925
A6
Intake Air Temp. Sensor
(built in Mass Air Flow Meter)
4
5 G±R
BR E2
THA ECM
20
E13
E13 28 5V
R
THA
E2
±
DIAGNOSTICS SFI SYSTEM(1ZZ±FE/3ZZ±FE)
05±31
AVENSIS REPAIR MANUAL (RM1018E)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

Read freeze frame data using \f \b\f\f
 Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, it is useful for d\
etermining whether the vehicle
was running or stopped, the engine was warmed up or not, the air±fuel ra\
tio was lean or rich, etc. at
the time of the malfunction.

If different DTCs that are related to a different system are output simultaneously while terminal E2 is
used as a ground terminal, terminal E2 may be open.
1READ VALUE OF HAND±HELD TESTER(INTAKE AIR TEMPERATURE)
(a)Connect the hand±held tester to the DLC3.
(b)Turn the ignition switch ON.
(c)Select the item ºDIAGNOSIS / OBD/MOBD / DATA LIST / ALL / INTAKE AIRº and read its value dis- played on the hand±held tester.
Temperature: The same as actual intake air temperature
Result:
Temperature DisplayedProceed to
±40 C (±40 F)A
140 C (284 F) or moreB
OK (Same as present temperature)C
HINT:

If there is an open circuit, the hand±held tester indicates ±40
C (±40
F).

If there is a short circuit, the hand±held tester indicates 140
C (284
F) or more.
BGo to step 4
CCHECK FOR INTERMITTENT PROBLEMS (See Page 05±5)
A