2005 TOYOTA AVENSIS heater

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
− DIAGNOSTICSSFI SYSTEM (2AZ−FSE)
05−83
AVENSIS Supplement (RM1045E)
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
to provide the ECM with feedback to 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 0.45 V). The ECM judges whether the air−fuel ratio is RICH or LEAN by voltage from the
heated oxygen sensor, and controls the injection timing accordingly. However, if the malfunction of the
heated oxygen sensor causes abnormal voltage output, the ECM becomes unable to perform the 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), the current flows
to the heater in order to heat the sensor for the accurate oxygen concentration detection.

05−84
− DIAGNOSTICSSFI SYSTEM (2AZ−FSE)
AVENSIS Supplement (RM1045E) DTC No.
DTC Detection ConditionTrouble Area
P0130
P0150After engine is warmed up, output voltage of heated oxygen
sensor remains at 0.4 V or more, or 0.55 V or less, during id-
ling (2 trip detection logic)
SOpen or short in heated oxygen sensor circuit
SHeated oxygen sensor (Bank1, 2 Sensor1)
SHeated oxygen sensor heater (Bank1, 2 Sensor1)
SEFI relay
SAir induction system
SFuel pressure
SInjector
SECM
P2195
P2197After engine is warmed up, output voltage of heated oxygen
sensor remains at 0.55 V or less, during idling (2 trip detection
logic)
SOpen or short in heated oxygen sensor circuit
SHeated oxygen sensor (Bank1, 2 Sensor1)
SHeated oxygen sensor heater (Bank1, 2 Sensor1)
SEFI relay
SAir induction system
SFuel pressure
SInjector
SECM
P2196
P2198After engine is warmed up, output voltage of heated oxygen
sensor remains at 0.4 V or more, during idling (2 trip detection
logic)
SOpen or short in heated oxygen sensor circuit
SHeated oxygen sensor (Bank1, 2 Sensor1)
SHeated oxygen sensor heater (Bank1, 2 Sensor1)
SEFI relay
SAir induction system
SFuel pressure
SInjector
SECM
HINT:
SBank1refers to the No.1and No. 4 cylinders.
SBank 2 refers to the No. 2 and No. 3 cylinders.
SSensor1refers to the sensor closest to the engine assembly.
SThe output voltage of the heated oxygen sensor and the short−term fuel trim value can be read using
the hand−held tester.

+25 %
−12.5 %
More than 0.5 V
Less than 0.4V
Case1
Case 2
Case 3
Case 4
Output voltage of heated oxygen
sensor (sensor1: front sensor)
Injection volume
Output voltage
Output voltage of heated oxygen
sensor (sensor 2: rear sensor)Main suspect
trouble area
OK
+25 %
−12.5 %
More than 0.5 V
Less than 0.4V
Injection volume
Output voltage
+25 %
−12.5 %
More than 0.5 V
Less than 0.4V
Injection volume
Output voltage
Sensor1: front sensor
(sensor1, heater, sensor1
circuit)+25 %
−12.5 %
More than 0.5 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
Almost no reaction


Sensor 2: rear sensor
(sensor 2, heater, sensor 2
circuit)
Almost no reaction Almost no reactionAlmost no reaction
− DIAGNOSTICSSFI SYSTEM (2AZ−FSE)
05−87
AVENSIS Supplement (RM1045E)
INSPECTION PROCEDURE
HINT:
Hand−held tester only:
It is possible the malfunctioning area can be found using the ACTIVE TEST A/F CONTROL operation. The
A/F CONTROL operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble
areas are malfunctioning or not.
(a) Perform the ACTIVE TEST A/F CONTROL operation.
HINT:
The A/F CONTROL operation lowers the injection volume12.5% or increases the injection volume 25%.
(1) Connect the hand−held tester to the DLC3 on the vehicle.
(2) Turn the ignition switch to ON.
(3) Warm up the engine by running the engine at 2,500 rpm for approximately 3 minutes.
(4) Select the item: DIAGNOSIS / OBD/MOBD / ACTIVE TEST / A/F CONTROL.
(5) Perform the A/F CONTROL operation 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 0.5 V
−12.5 %
lean output: Less than 0.4 V
NOTICE:
There is a delay of few seconds in the sensor1(front sensor) output, and there is about 20 seconds
delay at maximum in the sensor 2 (rear sensor).

A62378
1 2
3 4
+BHT
E1
OX
B1S1 H7
Heated Oxygen Sensor Component Side:
Front View
A79112
E1OX B2S1 H9
+B
HT Heated Oxygen Sensor
Component Side:
Front View
B16200
05−90
− DIAGNOSTICSSFI SYSTEM (2AZ−FSE)
AVENSIS Supplement (RM1045E)
5 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 (Bank1, 2 Sensor1):
Tester ConnectionResistance
1(HT)−2 (+B)11to16
at 20_C (68_F)
1(HT)−4(E1)10k
or higher
(c) Reconnect the heated oxygen sensor connector.
NG REPLACE HEATED OXYGEN SENSOR
OK
6 INSPECT EFI RELAY
(a) Remove the EFI relay from the engine room R/B No. 4.
(b) Check for continuity in the EFI relay.
Standard:
Tester ConnectionSpecified Condition
1−2Continuity
3−5No Continuity
3−5Continuity
(Apply battery voltage to terminals1and 2)
(c) Reinstall the EFI relay.
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 (Bank1Sensor1System 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
− DIAGNOSTICSSFI SYSTEM (2AZ−FSE)
05−91
AVENSIS Supplement (RM1045E)
7 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 the resistance between the wire harness side con-
nectors.
Standard (Check for open):
Tester ConnectionSpecified Condition
OX (H7−3)−OX1A(E12−22)Below1

HT (H7−1)−HT1A(E12−5)Below1

E1(H7−4)−E2 (E13−28)Below1

OX (H9−3)−OX2A (E12−23)Below1

HT (H9−1)−HT2A (E12−4)Below1

E1(H9−4)−E2 (E13−28)Below1

Standard (Check for short):
Tester ConnectionSpecified Condition
OX (H7−3) or OX1A(E12−22)−Body ground10k
or higher
HT (H7−1)orHT1A(E12−5)−Body ground10k
or higher
OX (H9−3) or OX2A (E12−23)−Body ground10k
or higher
HT (H9−1) or HT2A (E12−4)−Body ground10k
or higher
(d) Reconnect the heated oxygen sensor connector.
(e) Reconnect the ECM connector.
HINT:
SThe OX1A and HT1A means the heated oxygen sensor
bank1sensor1.
SThe OX2A and HT2A means the heated oxygen sensor
bank 2 sensor1.
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK

A80089
AB B+
Power Transistor
Platinum Hot Wire
(Heater)
Output
Voltage
Temperature
sensor
Platinum Hot Wire (Heater)
Temperature sensor
− DIAGNOSTICSSFI SYSTEM (2AZ−FSE)
05−55
AVENSIS Supplement (RM1045E)
DTC P0100 MASS OR VOLUME AIR FLOW CIRCUIT
DTC P0102 MASS OR VOLUME AIR FLOW CIRCUIT
LOW INPUT
DTC P0103 MASS OR VOLUME AIR FLOW CIRCUIT
HIGH INPUT
CIRCUIT DESCRIPTION
The MAF (Mass Air Flow) meter measures the amount of air flowing through the throttle valve. The ECM uses
this information to determine the fuel injection time and provide a proper air−fuel ratio. Inside the MAF meter,
there is a heated platinum wire exposed to the flow of intake air.
By applying a specific current to the wire, the ECM heats this wire to a given temperature. The flow of incom-
ing air cools the wire and an internal thermistor, changing their resistance. To maintain a constant current
value, the ECM varies the voltage applied to these components in the MAF meter. The voltage level is pro-
portional to the airflow through the sensor and the ECM interprets this voltage as the intake air amount.
The circuit is constructed so that the platinum hot wire and temperature sensor provide a bridge circuit, with
the power transistor controlled so that the potential of A and B remains equal to maintain the set temperature.
DTC No.DTC Detection ConditionTrouble Area
P0100Open or short in mass air flow meter circuit for more than 3
seconds at engine speed of 4,000 rpm or lessSOpen or short in mass air flow meter circuit
SMass air flow meter
SECM
P0102Open or short in mass air flow meter circuit for more than 3
seconds at engine speed of 4,000 rpm or less
SOpen in mass air flow meter circuit
SShort in ground circuit
SMass air flow meter
SECM
P0103
Open in mass air flow meter circuit for more than 3 seconds
(EVG circuit) at engine speed of 4,000 rpm or less
Short in mass air flow meter circuit for more than 3 seconds
(+B circuit) at engine speed of 4,000 rpm or lessSOpen in mass air flow meter circuit (EVG circuit)
SShort in mass air flow meter circuit (+B circuit)
SMass air flow meter
SECM
05CJE−02

− DIAGNOSTICSSFI SYSTEM (2AZ−FSE)
05−49
AVENSIS Supplement (RM1045E)
DTC P0031OXYGEN SENSOR HEATER CONTROL
CIRCUIT LOW (BANK1SENSOR1)
DTC P0032 OXYGEN SENSOR HEATER CONTROL
CIRCUIT HIGH (BANK1SENSOR1)
DTC P0037 OXYGEN SENSOR HEATER CONTROL
CIRCUIT LOW (BANK1SENSOR 2)
DTC P0038 OXYGEN SENSOR HEATER CONTROL
CIRCUIT HIGH (BANK1SENSOR 2)
DTC P0051OXYGEN SENSOR HEATER CONTROL
CIRCUIT LOW (BANK 2 SENSOR1)
DTC P0052 OXYGEN SENSOR HEATER CONTROL
CIRCUIT HIGH (BANK 2 SENSOR1)
DTC P0057 OXYGEN SENSOR HEATER CONTROL
CIRCUIT LOW (BANK 2 SENSOR 2)
DTC P0058 OXYGEN SENSOR HEATER CONTROL
CIRCUIT HIGH (BANK 2 SENSOR 2)
HINT:
SBank1refers to the No.1and No. 4 cylinders.
SBank 2 refers to the No. 2 and No. 3 cylinders.
SSensor1refers to the sensor closest to the engine assembly.
SSensor 2 refers to the sensor farthest away from the engine assembly.
05HI5−01

A72920
Reference (Bank1 Sensor 1 System Drawing)
Heated Oxygen Sensor
EFI Relay
Heater
SensorOX1A
HT
1A
Duty
Control
ECM
From
Battery EFI Fuse
E2
EFI No. 2
Fuse
MREL
OX HT
E 1
+B
05
−50
−
DIAGNOSTICS SFI SYSTEM (2AZ−FSE)
AVENSIS Supplement (RM 1045E)
CIRCUIT DESCRIPTION
Refer to DTC P0 130 on page 05 −82.
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
P003 1
P0037
P005 1
P0057( 1 ) Heated current is 0.2 A or less when heater operates with
+B voltage between 10.5 V and 11 .5 V ( 1 trip detection logic)
(2) Heated current is 0.25 A or less when heater operates with
+B greater than 11 .5 V ( 1 trip detection logic)S Open in heater circuit of heated oxygen sensor
S Heated oxygen sensor heater
S EFI relay
S EFI No. 2 fuse
S ECM
P0032
P0038
P0052
P0058
When heater operates, heater current exceeds 2 A
(1 trip detection logic)
S Short in heater circuit of heated oxygen sensor
S Heated oxygen sensor heater
S EFI relay
S ECM
WIRING DIAGRAM
Refer to DTC P0 130 on page 05 −82.
INSPECTION PROCEDURE
HINT:
SIf different DTCs related to different systems that have terminal E2 as the ground terminal are output
simultaneously, terminal E2 may have an open circuit.
SRead freeze frame data using the hand−held tester . Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the
vehicle was running or stopped, if the engine was warmed up or not, if the air −fuel ratio was lean or
rich, and other data from the time the malfunction occurred.