2005 TOYOTA AVENSIS heater

05±330
± DIAGNOSTICSSFI SYSTEM (1AZ±FSE)
AVENSIS REPAIR MANUAL (RM1018E)
DTC P0031 OXYGEN SENSOR HEATER CONTROL
CIRCUIT LOW (BANK 1 SENSOR 1)
DTC P0032 OXYGEN SENSOR HEATER CONTROL
CIRCUIT HIGH (BANK 1 SENSOR 1)
DTC P0037 OXYGEN SENSOR HEATER CONTROL
CIRCUIT LOW (BANK 1 SENSOR 2)
DTC P0038 OXYGEN SENSOR HEATER CONTROL
CIRCUIT HIGH (BANK 1 SENSOR 2)
DTC P0051 OXYGEN SENSOR HEATER CONTROL CIR-
CUIT LOW (BANK 2 SENSOR 1)
DTC P0052 OXYGEN SENSOR HEATER CONTROL
CIRCUIT HIGH (BANK 2 SENSOR 1)
DTC P0057 OXYGEN SENSOR HEATER CONTROL
CIRCUIT LOW (BANK 2 SENSOR 2)
DTC P0058 OXYGEN SENSOR HEATER CONTROL
CIRCUIT HIGH (BANK 2 SENSOR 2)
05CJD±01

A72920
Reference (Bank 1 Sensor 1 System Drawing)Heated Oxygen Sensor
EFI Relay
Heater
SensorOX1A HT1A
Duty
Control
ECM
From
Battery EFI Fuse
E2
EFI No. 2
Fuse
MREL
OX HT
E1
+B
±
DIAGNOSTICS SFI SYSTEM(1AZ±FSE)
05±331
AVENSIS REPAIR MANUAL (RM1018E)
CIRCUIT DESCRIPTION
Refer to DTC P0130 on page 05±363.
HINT:
The ECM provides a pulse width modulated control circuit to adjust current \
through the heater. The heated
oxygen sensor heater circuit uses a relay on the B+ side of the circuit.
DTC No.DTC Detection ConditionTrouble Area
P0031
P0037Heated current is 0.2 A or less when heater operates with +B >
10.5 V and < 11.5 V (1 trip detection logic)
Open in heater circuit of heated oxygen sensor

Heated oxygen sensor heater

EFI relay
P0037
P0051
P0057Heated current is 0.25 A or less when heater operates with +B

11.5 V (1 trip detection logic)
EFI relay

EFI fuse

EFI No. 2 fuse

ECM
P0032
P0038
P0052
P0058
Heated current exceeds 2 A when heater operates.
(1 trip detection logic)
Short in heater circuit of heated oxygen sensor

Heated oxygen sensor heater

ECM
HINT:

Bank 1 refers to the No. 1 and No. 4 cylinders.

Bank 2 refers to the No. 2 and No. 3 cylinders.

Sensor 1 refers to the sensor closest to the engine assembly.

Sensor 2 refers to the sensor farthest away from the engine assembly.
WIRING DIAGRAM
Refer to DTC P0130 on page 05±363.
INSPECTION PROCEDURE
HINT:

If different DTCs related to different systems that have terminal E2 as the ground terminal are output
simultaneously, terminal E2 may be open.

Read freeze frame data using the hand±held tester. Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, it is useful for deter\
mining 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.

A61830
+BHT
E1 Component Side
Heated Oxygen Sensor H9B2S1
A62378
+B
HT
E1


 
Component Side
Heated Oxygen Sensor H7B1S1
H8B1S2
H10
B2S2
B16200
05±332
± DIAGNOSTICSSFI SYSTEM (1AZ±FSE)
AVENSIS REPAIR MANUAL (RM1018E)
1 INSPECT HEATED OXYGEN SENSOR(HEATER RESISTANCE)
(a) Disconnect the H7, H8, H9 or H10 heated oxygen sensor
connector.
(b) Measure the resistance between the terminals of the
heated oxygen sensor connector.
Standard (Bank 2 sensor 1):
Terminal No.Resistance
1 (HT) ± 2 (+B)11 to 16
at 20
C (68
F)
1 (HT) ± 4 (E1)No Continuity
(c) Measure the resistance between the terminals of the
heated oxygen sensor connector.
Standard (Except Bank 2 sensor 1):
Terminal No.Resistance
1 (HT) ± 2 (+B)11 to 16
at 20
C (68
F)
1 (HT) ± 4 (E1)No Continuity
NG REPLACE HEATED OXYGEN SENSOR
OK
2 INSPECT EFI RELAY
(a) Remove the EFI relay from the engine room R/B No. 4.
(b) Inspect the EFI relay.
Standard:
Terminal No.Specified condition
1 ± 2Continuity
No Continuity
3 ± 5Continuity
(Apply battery voltage terminals 1 and 2)
NG REPLACE EFI RELAY
OK

05±394
± DIAGNOSTICSSFI SYSTEM (1AZ±FSE)
AVENSIS REPAIR MANUAL (RM1018E)
DTC P0171 SYSTEM TOO LEAN (BANK 1)
DTC P0172 SYSTEM TOO RICH (BANK 1)
DTC P0174 SYSTEM TOO LEAN (BANK 2)
DTC P0175 SYSTEM TOO RICH (BANK 2)
CIRCUIT DESCRIPTION
The fuel trim is related to the feedback compensation value, not to the basic injection time. The fuel trim in-
cludes the short±term fuel trim and the long±term fuel trim.
The short±term fuel trim is the short±term fuel compensation used to maintain the air±fuel ratio at stoichio-
metric air±fuel ratio. The signal from the heated oxygen sensor indicates whether the air±fuel ratio is RICH
or LEAN compared to the stoichiometric air±fuel ratio. This variance triggers a reduction in the fuel volume
if the air±fuel ratio is RICH, and an increase in the fuel volume if it is LEAN.
The long±term fuel trim is the overall fuel compensation carried out in long±term to compensate for a continu-
al deviation of the short±term fuel trim from the central value, due to individual engine differences, wear over-
time and changes in the operating environment.
If both the short±term fuel trim and the long±term fuel trim are LEAN or RICH beyond a certain value, it is
detected as a malfunction and the CHK ENG is illuminated.
DTC No.DTC Detection ConditionTrouble Area
P0171
P0174When air±fuel ratio feedback is stable after warming up engine,
fuel trim is considerably in error on LEAN side
(2 trip detection logic)

Air induction system

Injector blockage

Mass air flow meter

Manifold absolute pressure sensor

Engine coolant temperature sensor

Fuel pressure

Gas leakage in exhaust system

Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit

Heated oxygen sensor (bank 1, 2 sensor 1)

Heated oxygen sensor heater (bank 1, 2 sensor 1)

EFI relay

PCV valve and hose

PCV hose connection

ECM
P0172
P0175When air±fuel ratio feedback is stable after warming up engine,
fuel trim is considerably in error on RICH side
(2 trip detection logic)

Injector leakage blockage

Mass air flow meter

Manifold absolute pressure sensor

Engine coolant temperature sensor

Ignition system

Fuel pressure

Gas leakage in exhaust system

Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit

Heated oxygen sensor (bank 1, 2 sensor 1)

ECM
HINT:

When DTC ºP0171 or P0174º is recorded, the actual air±fuel ratio is on the LEAN side. When DTC
ºP0172 or P0175º is recorded, the actual air±fuel ratio is on the RICH side.

If the vehicle runs out of fuel, the air±fuel ratio is LEAN and DTC ºP0171 or P0174º is recorded. The
CHK ENG then comes on.
05CKD±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 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) 05±396
± DIAGNOSTICSSFI SYSTEM (1AZ±FSE)
AVENSIS REPAIR MANUAL (RM1018E)
The following A/F CONTROL procedure enables the technician to check and graph the voltage outputs of
both the heated oxygen sensors.
For displaying the graph indication, enter ºACTIVE TEST / A/F CONTROL / USER DATAº, then select ºO2S
B1S1 and O2S B1S2º or ºO2S B2S1 and O2S B2S2º by pressing ºYESº button and push ºENTERº button
before pressing ºF4º button.
HINT:

If different DTCs related to different systems that have terminal E2 as the ground terminal are output
simultaneously, terminal E2 may be open.

Read freeze frame data using the hand±held tester. 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.

A high heated oxygen sensor (sensor 1) voltage (0.55 V or more) could be caused by a rich air fuel
mixture. Check for conditions that would cause the engine to run rich.

A low heated oxygen sensor (sensor 1) voltage (0.4 V or less) could be caused by a lean air fuel mix-
ture. Check for conditions that would cause the engine to run lean.

A62378
Component Side
+B
HT
E1


 B1S1 H7
A61830
+B
HT
E1 Component Side
B2S1 H9
B16200
± DIAGNOSTICSSFI SYSTEM (1AZ±FSE)
05±403
AVENSIS REPAIR MANUAL (RM1018E)
21 INSPECT HEATED OXYGEN SENSOR(HEATER RESISTANCE)
(a) Disconnect the H7 or H9 heated oxygen sensor connec-
tor.
(b) Measure the resistance between the terminals of the
heated oxygen sensor connector.
Standard (Bank 1, 2 Sensor 1):
Terminal No.Resistance
1 (HT) ± 2 (+B)11 to 16
at 20
C (68
F)
1 (HT) ± 4 (E1)No Continuity
NG REPLACE HEATED OXYGEN SENSOR
OK
22 INSPECT EFI RELAY
(a) Remove the EFI relay from the engine room R/B No. 4.
(b) Inspect the EFI relay.
Standard:
Terminal No.Specified condition
1 ± 2Continuity
No Continuity
3 ± 5Continuity
(Apply battery voltage terminals 1 and 2)
NG REPLACE EFI RELAY
OK

A76821
Wire Harness Side
B1S1B2S1 H7 H9
Heated Oxygen Sensor Connector OX
HT
OX
HT
E1E1
A76823
OX2A
ECM Connector E12
OX1A
HT2A HT1A
E2 E13
A72920
Reference (Bank 1 Sensor 1 System Drawing)
Heated Oxygen Sensor
EFI Relay
Heater
Sensor
OX1A HT1A
Duty
Control ECM
From
Battery
EFI Fuse
E2 EFI No. 2
Fuse
MREL OX HT
E1 +B
05±404
± DIAGNOSTICSSFI SYSTEM (1AZ±FSE)
AVENSIS REPAIR MANUAL (RM1018E)
23 CHECK HARNESS AND CONNECTOR(HEATED OXYGEN SENSOR ± ECM)
(a) Disconnect the H7 or H9 heated oxygen sensor connec-
tor.
(b) Disconnect the E12 and E13 ECM connectors.
(c) Check for continuity between the wire harness side con-
nectors.
Standard (Check for open):
Symbols (Terminal No.)Specified condition
OX (H7±3) ± OX1A (E12±22)
HT (H7±1) ± HT1A (E12±5)
E1 (H7±4) ± E2 (E13±28)ContinuityOX (H8±3) ± OX2A (E12±23)Continuity
HT (H8±1) ± HT2A (E12±4)
E1 (H8±4) ± E2 (E13±28)
Standard (Check for short):
Symbols (Terminal No.)Specified condition
OX (H7±3) or OX1A (E12±22) ± Body ground
HT (H7±1) or HT1A (E12±5) ± Body groundNo continuityOX (H8±3) or OX2A (E12±23) ± Body groundNo continuity
HT (H8±1) or HT2A (E12±4) ± Body ground
HINT:

The OX1A and HT1A means the heated oxygen sensor
bank 1 sensor 1.

The OX2A and HT2A means the heated oxygen sensor
bank 2 sensor 1.
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
24 REPLACE HEATED OXYGEN SENSOR
GO

A00798
Atmosphere
Housing
Platinum Electrode
Solid Electrolyte
(Zirconia Element)
Platinum Electrode
Heater
Coating (Ceramic)
Exhaust Gas CoverIdeal Air±Fuel Mixture
Output Voltage
Richer ± Air Fuel Ratio ± Leaner
05±364
± DIAGNOSTICSSFI SYSTEM (1AZ±FSE)
AVENSIS REPAIR MANUAL (RM1018E)
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three±way cata-
lytic 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 will be vanished from
the exhaust gas. And the heated oxygen sensor informs the ECM of the RICH condition (high voltage, i.e.
more than 0.45 V). 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 abnormal 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 No.DTC Detection ConditionTrouble Area
P0130
P0150Output voltage of heated oxygen sensor (sensor 1) remains at
0.4 V or more, or 0.55 V or less, during idling after engine is
warmed up (2 trip detection logic)
Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit

Heated oxygen sensor (bank 1, 2 sensor 1)
P2195
P2197Output voltage of heated oxygen sensor (sensor 1) remains at
0.55 V or less, during idling after engine is warmed up (2 trip
detection logic)
Heated oxygen sensor (bank 1, 2 sensor 1)

Heated oxygen sensor heater (bank 1, 2 sensor 1)

EFI relay

Air induction system
P2196
P2198Output voltage of heated oxygen sensor (sensor 1) remains at
0.4 V or more, during idling after engine is warmed up (2 trip
detection logic)
y

Fuel pressure

Injector

ECM
HINT:

Bank 1 refers to the No. 1 and No. 4 cylinders.

Bank 2 refers to the No. 2 and No. 3 cylinders.

Sensor 1 refers to the sensor closest to the engine assembly.

The output voltage of the heated oxygen sensor and the short±term fuel trim value can be read using
the hand±held tester.