2005 TOYOTA AVENSIS fuel

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

+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

//
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

05–116
–
DIAGNOSTICS SFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
15 CHECK IF DTC OUTPUT RECURS(DTC P0171 AND/OR P0172)
(a) Connect the intelligent tester II to the DLC3.
(b) Turn the ignition switch to ON and turn the intelligent tester ll ON.
(c) Select the following menu items: Powertrain / Engine and ECT / DTC.
(d) Read DTCs. Result:
Display (DTC Output)Proceed To
No outputA
P0171 and/or P0172B
B REPLACE ECM AND PERFORM CONFIRMA- TION DRIVING PATTERN
(Refer to step 14)
A
16 CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST
NO CHECK FOR INTERMITTENT PROBLEMS (See page 05–9 )
YES
DTCS ARE CAUSED BY RUNNING OUT OF FUEL (DTCS P0171 AND/OR P0172)
17 PERFORM CONFIRMATION DRIVING PATTERN
HINT:
Clear all DTCs prior to performing the confirmation driving pattern (re\
fer to step 14). GO
18 CHECK IF DTC OUTPUT RECURS(DTC P0171 AND/OR P0172)
(a) Connect the intelligent tester II to the DLC3.
(b) Turn the ignition switch to ON and turn the intelligent tester ll ON.
(c) Select the following menu items: Powertrain / Engine and ECT / DTC.
(d) Read DTCs. Result:
Display (DTC Output)Proceed To
P0171 and/or P0172A
No outputB
B Go to step 22
A

–
DIAGNOSTICS SFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
05–117
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
19 REPLACE HEATED OXYGEN SENSOR
GO
20 PERFORM CONFIRMATION DRIVING PATTERN
HINT:
Clear all DTCs prior to performing the confirmation driving pattern (refer t\
o step 14).
GO
21 CHECK IF DTC OUTPUT RECURS(DTC P0171 AND/OR P0172)
(a) Connect the intelligent tester II to the DLC3.
(b) Turn the ignition switch to ON and turn the intelligent tester ll ON.
(c) Select the following menu items: Powertrain / Engine and ECT / DTC.
(d) Read DTCs. Result:
Display (DTC Output)Proceed To
No outputA
P0171 and/or P0172B
B REPLACE ECM AND PERFORM CONFIRMA- TION DRIVING PATTERN
(Refer to step 14)
A
22 CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST
NO CHECK FOR INTERMITTENT PROBLEMS
( See page 05–9 )
YES
DTCS ARE CAUSED BY RUNNING OUT OF FUEL (DTCS P0171 AND/OR P0172)

A93651
+B HT
E1 OX Component Side:
Front View
Heated Oxygen Sensor Connector
+B HT
E1 OX
w/ HID w/o HID
Sensor 2
B16200
A18294
HT1B (+)
E03 (–)
E12
E9
ECM Connector
– DIAGNOSTICSSFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
05–47
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
INSPECTION PROCEDURE
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.
1 INSPECT HEATED OXYGEN SENSOR(HEATER RESISTANCE)
(a) Disconnect the H17 heated oxygen sensor connector.
(b) Measure the resistance between the terminals of the
heated oxygen sensor connector.
Standard:
Tester ConnectionSpecified Condition
With HID: 1 (HT) – 2 (+B)11 to 16 Ω at 20C (68F)
With HID: 1 (HT) – 4 (E1)No Continuity
Without HID: 2 (HT) – 1 (+B)11 to 16 Ω at 20C (68F)
Without HID: 2 (HT) – 3 (E1)No Continuity
(c) Reconnect the heated oxygen sensor connector.
NG REPLACE HEATED OXYGEN SENSOR
OK
2 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
3 INSPECT ECM(HT1B VOLTAGE)
(a) Turn the ignition switch to ON.
(b) Measure the voltage between the applicable terminals of
the E9 and E12 ECM connectors.
Standard:
Tester ConnectionSpecified Condition
HT1B (E9–7) – E03 (E12–7)9 to 14 V

A93649
HT
+B
E1
OX Sensor 1Heated Oxygen Sensor Connector Component Side:
Front View
B16200
A18294
OX1A (+) E12
ECM Connector
HT1A (+)
E13
E2 (–)
E03
05–44
– DIAGNOSTICSSFI SYSTEM (1ZZ–FE/3ZZ–FE)(From February, 2004)
AVENSIS REPAIR MANUAL SUPPLEMENT
(RM1098E)
INSPECTION PROCEDURE
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.
1 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 (Sensor 1):
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
2 INSPECT EFI RELAY
(a) Remove the EFI relay from the engine room R/B.
(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
3 INSPECT ECM(HT1A VOLTAGE)
(a) Turn the ignition switch to ON.
(b) Measure the voltage between the applicable terminals of
the E12 and E13 ECM connectors.
Standard:
Tester ConnectionSpecified Condition
HT1A (E12–6) – E03 (E12–7)9 to 14 V
OX1A (E12–22) – E2 (E13–28)9 to 14 V
OK REPLACE ECM (See page 10–65 of Pub. No.
RM1018E AVENSIS)
NG