2005 TOYOTA AVENSIS fuel

±
DIAGNOSTICS SFI SYSTEM(1ZZ±FE/3ZZ±FE)
05±67
AVENSIS REPAIR MANUAL (RM1018E)
DTCP0171SYSTEM TOO LEAN (FUEL TRIM) (BANK 1)
DTCP0172SYSTEM TOO RICH (FUEL TRIM) (BANK 1)
CIRCUIT DESCRIPTION
Fuel trim refers to the feedback compensation value compared against the basic injection time. Fuel trim
includes short±term fuel trim and long±term fuel trim.
Short±term fuel trim is the short±term fuel compensation used to maintain the a\
ir±fuel ratio at stoichiometric
air±fuel ratio. The signal from the heated oxygen sensor indicates whether the a\
ir±fuel ratio is RICH or LEAN
compared to the stoichiometric air±fuel ratio, This variance triggers a reduc\
tion in fuel volume if the air±fuel
ratio is rich, and an increase in the fuel volume if it is lean.
Long±term fuel trim is overall fuel compensation carried out long±term to comp\
ensate for a continual devi-
ation of the short±term fuel trim from the central value, due to indi\
vidual engine differences, wear over time
and changes in the operating environment.
If both the short±term fuel trim and long±term fuel trim are LEAN or RICH beyond a certain value, it is de\
-
tected as a malfunction and the CHK ENG is illuminated.
DTC No.DTC Detecting 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

PCV hose

Mass air flow meter

Engine coolant temperature sensor

Fuel pressure

Open or short in heated oxygen sensor circuit

Heated oxygen sensor

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 leak, blockage

Mass air flow meter

Engine coolant temperature sensor

Ignition system

Fuel pressure

Open or short in heated oxygen sensor circuit

Gas leakage in exhaust system

Heated oxygen sensor

ECM
HINT:
If the total of the short±term fuel trim value and long±term fuel \
trim value is within
25 %, the system is func-
tioning normally.
WIRING DIAGRAM
Refer to DTC P0125 on page 05±45.
05B3Y±02

+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 of the
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±68
± DIAGNOSTICSSFI SYSTEM (1ZZ±FE/3ZZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
INSPECTION PROCEDURE
HINT:
Hand±held tester only:
Narrowing down the trouble area is possible by performing ACTIVE TEST of the following ºA/F CONTROLº
(heated oxygen sensor or other trouble areas can be distinguished).
(a) Perform ACTIVE TEST using the hand±held tester (A/F CONTROL).
HINT:
ºA/F CONTROLº is an ACTIVE TEST which changes the injection volume ±12.5 % or +25 %.
(1) Connect the hand±held tester to the DLC3 on the vehicle.
(2) Turn the ignition switch ON.
(3) Warm up the engine with the engine speed at 2,500 rpm for approximately 90 sec.
(4) Select the item ºDIAGNOSIS / OBD/MOBD / ACTIVE TEST / A/F CONTROLº.
(5) Perform ºA/F CONTROLº 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 0.55 V
±12.5 %
lean output: Less than 0.4 V
NOTICE:
There is a few second delay in the sensor 1 (front sensor) output, and there is about 20 seconds delay
in the sensor 2 (rear sensor) output.

±
DIAGNOSTICS SFI SYSTEM(1ZZ±FE/3ZZ±FE)
05±69
AVENSIS REPAIR MANUAL (RM1018E)
The following procedure of A/F CONTROL enable the technician to check and graph voltage output of the
heated oxygen sensor.
For displaying the graph indication, enter ºACTIVE TEST / A/F CONTROL / \
USER DATA,º then select ºO2S
B1S1 and O2S B1S2º by pressing ºYESº button and push ºENTERº \
button before pressing ºF4º button.
HINT:

If different DTCs that are related to a different system are output simultaneously while terminal E2 is
used as a ground terminal, terminal E2 may be open.

Read freeze frame data using \f \b\f\f
 Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, it is useful for d\
etermining 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.

A high heated oxygen sensor (sensor 1) voltage (0.55 V or more) coul\
d 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 b\
e caused by a lean air fuel mix-
ture. Check for conditions that would cause the engine to run lean.
1CHECK AIR INDUCTION SYSTEM
(a)Check for vacuum leaks in air induction system.
NGREPAIR OR REPLACE AIR INDUCTION SYSTEM
OK
2INSPECT FUEL INJECTOR ASSY(INJECTION AND VOLUME) (See page 11±8)
NGREPLACE FUEL INJECTOR ASSY
OK
3INSPECT MASS AIR FLOW METER (See page 10±3)
NGREPLACE MASS AIR FLOW METER
OK
4INSPECT ENGINE COOLANT TEMPERATURE SENSOR(RESISTANCE) (See page 10±3)
NG REPLACE ENGINE COOLANT TEMPERATURE SENSOR
OK
5CHECK FOR SPARK AND IGNITION (See page 18±1)
NG REPAIR OR REPLACE
OK

05±70
±
DIAGNOSTICS SFI SYSTEM(1ZZ±FE/3ZZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
6CHECK FUEL PRESSURE (See page 11±5)
(a)Check the fuel pressure (high or low pressure). NGCHECK AND REPLACE FUEL SYSTEM
OK
7CHECK FOR EXHAUST GAS LEAKAGE
NGREPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK
8READ VALUE OF HAND±HELD TESTER(OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR) (See page 05±54)
OKGo to step 18
NG
9INSPECT HEATED OXYGEN SENSOR(HEATER RESISTANCE) (See page 05±45)
NGREPLACE HEATED OXYGEN SENSOR
OK
10INSPECT EFI RELAY (See page 10±3)
NGREPLACE EFI RELAY
OK
11CHECK FUSE(EFI No.2) (See page 05±45)
NGCHECK FOR SHORT IN ALL HARNESS AND COMPONENTS CONNECTED FUSE
OK
12CHECK HARNESS AND CONNECTOR(HEATED OXYGEN SENSOR ± ECM) (See page 05±45)
NG REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

±
DIAGNOSTICS SFI SYSTEM(1ZZ±FE/3ZZ±FE)
05±71
AVENSIS REPAIR MANUAL (RM1018E)
13CHECK HARNESS AND CONNECTOR(EFI RELAY ± HEATED OXYGEN SENSOR)
(See page 05±45)
NGREPAIR OR REPLACE HARNESS OR
CONNECTOR
OK
14REPLACE HEATED OXYGEN SENSOR
GO
15PERFORM CONFIRMATION DRIVING PATTERN (See page 05±54)
GO
16READ OUTPUT DTC(DTC P0171 AND/OR P0172 ARE OUTPUT AGAIN)
(a)Read the DTC using the hand±held tester. Result:
Display (DTC output)Proceed to
DTC ºP0171 and/or P0172º are not output againA
DTC ºP0171 and/or P0172º are output againB
BCHECK AND REPLACE ECM (See page 01±32) AND PERFORM CONFIRMATION DRIV-
ING PATTERN (See page 05±54)
A
17CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST
NOCHECK FOR INTERMITTENT PROBLEMS (See page 05±5)
YES
DTC IS CAUSED BY RUNNING OUT OF FUEL (DTCS P0171 AND/OR P0172)
18PERFORM CONFIRMATION DRIVING PATTERN (See page 05±54)
GO

05±72
±
DIAGNOSTICS SFI SYSTEM(1ZZ±FE/3ZZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
19READ OUTPUT DTC(DTC P0171 AND/OR P0172 ARE OUTPUT AGAIN)
(a)Read the DTC using the hand±held tester. Result:
Display (DTC output)Proceed to
DTC ºP0171 and/or P0172º are not output againA
DTC ºP0171 and/or P0172º are output againB
BGo to step 22
A
20REPLACE HEATED OXYGEN SENSOR
GO
21READ OUTPUT DTC(DTC P0171 AND/OR P0172 ARE OUTPUT AGAIN)
(a)Read the DTC using the hand±held tester. Result:
Display (DTC output)Proceed to
DTC ºP0171 and/or P0172º are not output againA
DTC ºP0171 and/or P0172º are output againB
BCHECK AND REPLACE ECM (See page 01±32) AND PERFORM CONFIRMATION DRIV-
ING PATTERN (See page 05±54)
A
22 CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST
NO CHECK FOR INTERMITTENT PROBLEMS (See Page 05±5)
YES
DTC IS CAUSED BY RUNNING OUT OF FUEL

±
DIAGNOSTICS SFI SYSTEM(1ZZ±FE/3ZZ±FE)
05±65
AVENSIS REPAIR MANUAL (RM1018E)
DTCP0135OXYGEN SENSOR HEATER CIRCUIT
MALFUNCTION (BANK 1 SENSOR 1)
DTCP0141OXYGEN SENSOR HEATER CIRCUIT MALFUNCTION (BANK 1 SENSOR 2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page 05±45.
DTC No.DTC Detecting ConditionTrouble Area
P0135

When the heater operates, heater current exceeds 3.5 A
(1 trip detection logic)

Heater current is 0.2 A or less when the heater operates
(1 trip detection logic)
Open or short in heater circuit of heated oxygen sensor

Heated oxygen sensor heater

ECM
P0141

When the heater operates, heater current exceeds 2 A
(1 trip detection logic)

Heater current is 0.2 A or less when the heater operates
(1 trip detection logic)
Open or short in heater circuit of heated oxygen sensor

Heated oxygen sensor heater

ECM
WIRING DIAGRAM
Refer to DTC P0125 on page 05±45.
INSPECTION PROCEDURE
HINT:

If different DTCs that are related to a different system are output simultaneously while terminal E2 is
used as a ground terminal, terminal E2 may be open.

Read freeze frame data using \f \b\f\f
 Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, it is useful for d\
etermining 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.
1INSPECT HEATED OXYGEN SENSOR(HEATER RESISTANCE) (See page 05±45)
NG REPLACE HEATED OXYGEN SENSOR
OK
2INSPECT EFI RELAY (See page 10±3)
NG REPLACE EFI RELAY
OK
3CHECK FUSE(EFI No.2) (See page 05±45)
NG CHECK FOR SHORT IN ALL HARNESS AND COMPONENTS CONNECTED FUSE
OK
05C6A±01

05±60
±
DIAGNOSTICS SFI SYSTEM(1ZZ±FE/3ZZ±FE)
AVENSIS REPAIR MANUAL (RM1018E)
DTCP0133OXYGEN SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 1)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page 05±45.
DTC NoDTC Detecting ConditionTrouble Area
P0133
Response time for heated oxygen sensor voltage output to
change from rich to lean, or from lean to rich, is 1.0 sec. or
more during idling after engine is warmed up (2 trip detection
logic)

Open or short in heated oxygen sensor circuit

Heated oxygen sensor

Air induction system

Fuel pressure

Injector

ECM
HINT:

 


 \f
\f















\b


\f

 
\f


 
 

\f
 \f
\f


WIRING DIAGRAM
Refer to DTC P0125 on page 05±45.
INSPECTION PROCEDURE
HINT:
Hand±held tester only:
Narrowing down the trouble area is possible by performing ACTIVE TEST of the following \
ºA/F CONTROLº
(heated oxygen sensor or other trouble areas can be distinguished).
(a) Perform ACTIVE TEST using hand±held tester (A/F CONTROL).
HINT:
ºA/F CONTROLº is an ACTIVE TEST which changes the injection volume\
±12.5 % or +25 %.
(1) Connect the hand±held tester to the DLC3 on the vehicle.
(2) Turn the ignition switch ON.
(3) Warm up the engine with the engine speed at 2,500 rpm for approximately. 90 sec.
(4) Select the item ºDIAGNOSIS / OBD/MOBD / ACTIVE TEST / A/F CONTROLº\
.
(5) Perform ºA/F CONTROLº 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 0.55 V
±12.5 %
lean output: Less than 0.4 V
NOTICE:
There is a few second delay in the sensor 1 (front sensor) output, and ther\
e is about 20 seconds delay
in the sensor 2 (rear sensor) output.
05B3W±02