2005 TOYOTA AVENSIS Service Repair Manual

wheel size dead battery open trunk alarm fuel consumption adblue change key battery

Page 529 of 5135

TOYOTA AVENSIS 2005 Service Repair Manual 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

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

Page 530 of 5135

$TOYOTA AVENSIS 2005 Service Repair Manual ± DIAGNOSTICS SFI SYSTEM(1AZ±FSE) 05±395 AVENSIS REPAIR MANUAL (RM1018E) If the total of the short±term fuel trim value and long±term fuel tri\ m value is within 25 % (Engine cool- ant temp$

Page 531 of 5135

TOYOTA AVENSIS 2005 Service Repair Manual +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 oxy

+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.

Page 532 of 5135

TOYOTA AVENSIS 2005 Service Repair Manual ±
DIAGNOSTICS SFI SYSTEM(1AZ±FSE)
05±397
AVENSIS REPAIR MANUAL (RM1018E)
1CHECK OTHER DTC OUTPUT(IN ADDITION TO DTC P0171, P0172, P0174
AND/OR P0175)
(a)Read the DTC using the hand±held tester.

Page 533 of 5135

TOYOTA AVENSIS 2005 Service Repair Manual 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
TEMPERATUREC(F)
RESISTANCE k
(±4) (32) (80) (140)(104) (212)(176)
Air
VG
E2G+B
THA E2
Acceptable
05±398
± DIAGNOSTICSSFI SY

Page 534 of 5135

TOYOTA AVENSIS 2005 Service Repair Manual
3020
10
5
3
02040
0.1 1
0.3 0.2
0.5 2
6080100
±20
(±4)(104)(140)(176) (32)(68)(212)
30
20
10
5
3
02040
0.1 1
0.3 0.2
0.5 2
6080100
±20
(±4)(104)(140)(176) (32)(68)(212)
A8

Page 535 of 5135

TOYOTA AVENSIS 2005 Service Repair Manual 05±400
±
DIAGNOSTICS SFI SYSTEM(1AZ±FSE)
AVENSIS REPAIR MANUAL (RM1018E)
9CHECK FOR EXHAUST GAS LEAKAGE
NGREPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT (See page 15±6)
OK
10 CONFIRM IF ANY MISFIRI

Page 536 of 5135

TOYOTA AVENSIS 2005 Service Repair Manual P18349
±
DIAGNOSTICS SFI SYSTEM(1AZ±FSE)
05±401
AVENSIS REPAIR MANUAL (RM1018E)
14READ VALUE OF HAND±HELD TESTER(OUTPUT VOLTAGE OF HEATED OXYGEN
SENSOR (BANK 1, 2 SENSOR 1))
(a)Warm up the heate

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