TOYOTA AVENSIS 2005 Service Repair Manual

05–106
–
DIAGNOSTICS SFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
DTC P0171 SYSTEM TOO LEAN (BANK 1)
DTC P0172 SYSTEM TOO RICH (BANK 1)
CIRCUIT DESCRIPTION
The fuel trim is related to the feedback compensation value, not to the bas\
ic 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 its ideal
theoretical value. The signal from the heated oxygen sensor indicates whether the air–fuel r\
atio is rich or
lean compared to the ideal theoretical value, triggering 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 in order to bal\
ance the short–term fuel trim for a
continual deviation from the central value by individual engine differences, operating environment and age
deterioration.
If both the short–term fuel trim and the long–term fuel trim are l\
ean or rich beyond a standard level, it is de-
tected as a malfunction in the SFI system. The ECM illuminates the MIL and the\
DTC is set.
DTC No.DTC Detection ConditionTrouble Area
P0171
When 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
 Engine coolant temperature sensor
 Fuel pressure
 Gas leakage in exhaust system
 Open or short in heated oxygen sensor (sensor 1) circuit
 Heated oxygen sensor (sensor 1)
 PCV valve and hose
 PCV hose connection
 ECM
P0172
When 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 or blockage
 Mass air flow meter
 Engine coolant temperature sensor
 Ignition system
 Fuel pressure
 Gas leakage in exhaust system
 Open or short in heated oxygen sensor (sensor 1) circuit
 Heated oxygen sensor (sensor 1)
 ECM
HINT:
When DTC P0171 is set, the actual air–fuel ratio is lean. When DTC P0172 is set, the actual air–fuel\

ratio is rich.
If the vehicle runs out of fuel, the air–fuel ratio is lean and DTC P01\
71 may be set. The MIL then illumi-
nates.
If the total of the short–term fuel trim value and long–term fuel trim value is within
20 %, the system
is functioning normally.
WIRING DIAGRAM
Refer to DTC P0130 on page 05–74.
05KO5–02

– DIAGNOSTICSSFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
05–107
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
INSPECTION PROCEDURE
HINT:
Intelligent tester II only:
Malfunctioning areas can be found using the Active Test / A/F Control operation. The A/F Control operation
can determine if the heated oxygen sensor or other potential trouble areas are malfunctioning or not.
(a) Perform the Active Test using the intelligent tester II.
HINT:
The A/F Control operation lowers the injection volume by 12.5 % or increases the injection volume by 25
%.
(1) Connect the intelligent tester II to the DLC3.
(2) Start the engine and turn the intelligent tester II ON.
(3) Warm up the engine by running the engine at 2,500 rpm for approximately 3 minutes.
(4) On the intelligent tester II, select the following menu items: Powertrain / Engine and ECT / Active
Test / A/F Control.
(5) Select the following monitor items: O2S B1 S1 and O2S B1 S2.
(6) Perform the A/F Control operation with the engine in an idling condition (press the right or left
button).
Result:
The heated oxygen sensor reacts in accordance with increases and decreases of the injection
volume:
+25 % → Rich output: More than 0.5 V
–12.5 % → Lean output: Less than 0.4 V
NOTICE:
Sensor 1 (front sensor) has an output delay of a few seconds. Sensor 2 (rear sensor) has a maximum
output delay of approximately 20 seconds.

+25 %
–12.5 %
More than 0.5 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)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
Sensor 1: front sensor
(Sensor 1, heater, sensor 1
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
05–108
– DIAGNOSTICSSFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
The following A/F Control procedure enables the technician to check and graph the voltage output of both
the heated oxygen sensors.
To display the graph, select the following menu items on the tester: View / Line Graph.
NOTICE:
If the vehicle is short of fuel, the air–fuel ratio becomes lean and the heated oxygen sensor DTCs will
be recorded, and the MIL then illuminates.
HINT:
Read freeze frame data using the intelligent tester II. Freeze frame data record the engine condition
when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the
vehicle was moving or stationary, 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.
A high heated oxygen sensor (sensor 1) voltage (0.5 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.

– DIAGNOSTICSSFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
05–109
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
1 CHECK AIR INDUCTION SYSTEM
(a) Check for vacuum leaks in the air induction system.
OK: No vacuum leak.
NG REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK
2 CHECK CONNECTION OF PCV HOSE
OK: The PCV hose is connected correctly and not damaged.
NG REPAIR OR REPLACE PCV HOSE
OK
3 INSPECT FUEL INJECTOR ASSY(INJECTION AND VOLUME)
(See page 11–8 of Pub. No. RM1018E AVENSIS)
NG REPLACE FUEL INJECTOR ASSY
(See page 11–10 of Pub. No. RM1018E AVENSIS)
OK

A60548
32 1 4 5
–20 0 20 40 60 80 100 0.1 0.2 0.3 0.51 2 3 5 10 20 30
(–4) (32) (68) (140)(104) (212)(176)
Air
VG
E2G+B
THA E2
Acceptable
Temperature C (F)
Resistance kΩ
05–110
– DIAGNOSTICSSFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
4 INSPECT MASS AIR FLOW METER
(a) Remove the mass air flow meter.
(b) Inspect output voltage.
(1) Apply the battery voltage across terminals +B and
E2G.
(2) Connect the positive (+) tester probe to terminal
VG, and negative (–) tester probe to terminal E2G.
(3) Blow air into the mass air flow meter, and check that
the voltage fluctuates.
(c) Inspect the resistance.
(1) Measure the resistance between the terminals of
the intake air temperature sensor.
Standard:
Tester ConnectionSpecified Condition
THA (4) – E2 (5)13.6 to 18.4 kΩ at –20C (–4F)
THA (4) – E2 (5)2.21 to 2.69 kΩ at 20C (68F)
THA (4) – E2 (5)0.49 to 0.67 kΩ at 60C (140F)
(d) Reinstall the mass air flow meter.
NG REPLACE MASS AIR FLOW METER
OK

//
30
20
10
5
3
02040 0.11
0.3
0.2 0.52
60 80 100 –20
(–4) (104) (140) (176)(32) (68) (212)
A81700
Ohmmeter
Acceptable
Temperature C (F)
Resistance kΩ
– DIAGNOSTICSSFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
05–111
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
5 INSPECT ENGINE COOLANT TEMPERATURE SENSOR(RESISTANCE)
(a) Remove the engine coolant temperature sensor.
(b) Measure the resistance between the terminals of the en-
gine coolant temperature sensor.
Standard:
Tester ConnectionSpecified Condition
1 – 22.32 to 2.59 kΩ at 20C (68F)
1 – 20.310 to 0.326 kΩ at 80C (176F)
NOTICE:
When checking the engine coolant temperature sensor in
water, be careful not to allow water to get in contact with the
terminals. After checking, dry the sensor.
HINT:
Alternative procedure: Connect an ohmmeter to the installed
engine coolant temperature sensor and read the resistance.
Use an infrared thermometer to measure the engine tempera-
ture in the immediate vicinity of the sensor. Compare these val-
ues against the resistance/temperature graph. Change the en-
gine temperature (warm up or allow to cool down) and repeat
the test.
NG REPLACE ENGINE COOLANT TEMPERATURE
SENSOR
OK
6 CHECK FOR SPARK AND IGNITION
(See page 18–3 of Pub. No. RM1018E AVENSIS)
OK: The spark occurs.
NG REPAIR OR REPLACE
OK
7 CHECK FUEL PRESSURE (See page 11–5 of Pub. No. RM1018E AVENSIS)
(a) Check the fuel pressure (high or low pressure).
NG CHECK AND REPLACE FUEL SYSTEM
OK
8 CHECK FOR EXHAUST GAS LEAKAGE
OK: No gas leak.
NG REPAIR OR REPLACE EXHAUST GAS
LEAKAGE POINT
OK

A97090
A93649
+B HT
E1 Component Side:
Front View Heated Oxygen Sensor Connector
Sensor 1
OX
05–112
– DIAGNOSTICSSFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
9 READ VALUE OF INTELLIGENT TESTER II(OUTPUT VOLTAGE OF HEATED
OXYGEN SENSOR)
(a) Connect the intelligent tester II to the DLC3.
(b) Start the engine and turn the intelligent tester II ON.
(c) Select the following menu items: Powertrain / Engine and ECT / Data List / O2S B1 S1.
(d) Warm up the heated oxygen sensor at the engine speed of 2,500 rpm for approximately 90 seconds.
(e) Read the output voltage of the heated oxygen sensor during engine idling.
Standard:
Fluctuates between less than 0.4 V and more than 0.5 V (see the following figure).
OK Go to step 17
NG
10 INSPECT HEATED OXYGEN SENSOR(HEATER RESISTANCE)
(a) Disconnect the H7 heated oxygen sensor connector.
(b) Measure the resistance between the terminals of the
heated oxygen sensor connector.
Standard:
Tester ConnectionSpecified Condition
1 (HT) – 2 (+B)5 to 10 Ω at 20C (68F)
1 (HT) – 4 (E1)10 kΩ or higher
(c) Reconnect the heated oxygen sensor connector.
NG REPLACE HEATED OXYGEN SENSOR
OK

B16200
– DIAGNOSTICSSFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
05–113
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
11 INSPECT EFI RELAY
(a) Remove the EFI relay from the engine room R/B No. 4.
(b) Check the EFI relay resistance.
Standard:
Tester ConnectionSpecified Condition
3 – 510 kΩ or higher
3 – 5Below 1 Ω
(Apply battery voltage to terminals 1 and 2)
(c) Reinstall the EFI relay.
NG REPLACE EFI RELAY
OK

A79114
Wire Harness Side:
Sensor 1H7
Heated Oxygen Sensor Connector
HT
OX
E1
Front View
A65746
HT1A
ECM Connector E12
OX1AE2 E13
A78602
Reference (Sensor 1 System Diagram):
Heated Oxygen Sensor
EFI Relay
Heater
Sensor
OX1A HT1AECM
From
Battery
EFI Fuse
E2
MREL OX HT
E1 +B
05–114
– DIAGNOSTICSSFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
12 CHECK HARNESS AND CONNECTOR(HEATED OXYGEN SENSOR – ECM)
(a) Disconnect the H7 heated oxygen sensor connector.
(b) Disconnect the E12 and E13 ECM connectors.
(c) Check the resistance.
Standard (Check for open):
Tester ConnectionSpecified Condition
OX (H7–3) – OX1A (E12–22)Below 1 Ω
HT (H7–1) – HT1A (E12–6)Below 1 Ω
E1 (H7–4) – E2 (E13–28)Below 1 Ω
Standard (Check for short):
Tester ConnectionSpecified Condition
OX (H7–3) or OX1A (E12–22) – Body ground10 kΩ or higher
HT (H7–1) or HT1A (E12–6) – Body ground10 kΩ or higher
(d) Reconnect the heated oxygen sensor connector.
(e) Reconnect the ECM connector.
NG REPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
13 REPLACE HEATED OXYGEN SENSOR
GO

A58686
Vehicle Speed48 km/h
(30 mph)
Ignition Switch OFF 40 seconds
or more
Engine coolant temperature is more than 75
C (167 F)
20 seconds
or more 40 seconds
or more
40 seconds
or more
(g) (h)
Idling (e) (g)
(h) (g)
(h)
20 seconds
or more 20 seconds
or more
Once
Twice
At least 8 times
2 minutes
or more
(a), (b) and (c)
–
DIAGNOSTICS SFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
05–115
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
14 PERFORM CONFIRMATION DRIVING PATTERN
(a) Connect the intelligent tester II to the DLC3.
(b) Turn the ignition switch to ON and turn the intelligent tester ll ON.
(c) Switch the ECM from normal mode to check mode using the intelligent test\
er ll ( see page 05–20).
(d) Start the engine.
(e) Allow the engine to idle for 2 minutes.
(f) Warm up the engine until the engine coolant temperature reaches more than\
75 C (167 F).
(g) Drive the vehicle at 48 km/h (30 mph) or more for 40 seconds or more.
(h) Stop the vehicle and allow the engine to idle for 20 seconds or more.
(i) Repeat the steps (g) and (h) at least 8 times in one driving cycle.
HINT:
If a malfunction exists, the MIL will be illuminated during step (i).
NOTICE:
If the conditions in this test are not strictly followed, no malfunction\
will be detected. If you do not
have the intelligent tester II, turn the ignition switch to OFF after perfor\
ming steps from (d) to (i), then
perform steps (d) to (i) again.
GO