Component DescriptionNLEC0153The heated oxygen sensor 2 (rear), after three way catalyst, moni-
tors the oxygen level in the exhaust gas.
Even if switching characteristics of the heated oxygen sensor 1
(front) are shifted, the air fuel ratio is controlled to stoichiometric,
by the signal from the heated oxygen sensor 2 (rear).
This sensor is made of ceramic zirconia. The zirconia generates
voltage from approximately 1V in richer conditions to 0V in leaner
conditions.
Under normal conditions the heated oxygen sensor 2 (rear) is not
used for engine control operation.
CONSULT-II Reference Value in Data Monitor
Mode
NLEC0154Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 (B1)
IEngine: After warming upRevving engine from idle to 3,000
rpm0 - 0.3V+,Approx. 0.6 - 1.0V
HO2S2 MNTR
(B1)LEAN+,RICH
ECM Terminals and Reference ValueNLEC0155Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
63 LHeated oxygen sensor 2
(rear)[Engine is running]
IAfter warming up to normal operating temperature
and engine speed is 2,000 rpm0 - Approximately 1.0V
On Board Diagnosis LogicNLEC0156The heated oxygen sensor 2 (rear) has a much longer switching
time between rich and lean than the heated oxygen sensor 1
(front). The oxygen storage capacity before the three way catalyst
causes the longer switching time. To judge the malfunctions of
heated oxygen sensor 2 (rear), ECM monitors whether the maxi-
mum voltage of the sensor is sufficiently high during various driv-
ing conditions such as fuel-cut.
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0138
0138IThe maximum voltage from the sensor does not reach
the specified voltage.IHarness or connectors
(The sensor circuit is open or shorted.)
IHeated oxygen sensor 2 (rear)
IFuel pressure
IInjectors
IIntake air leaks
SEF327R
SEF259VA
DTC P0138 HEATED OXYGEN SENSOR 2 (REAR)
(MAX. VOLTAGE MONITORING)QG16I18DE
Component Description
EC-180
2 CLEAR THE SELF-LEARNING DATA
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªSELF-LEARNING CONTº in ªWORK SUPPORTº mode with CONSULT-II.
3. Clear the self-learning control coefficient by touching ªSTARTº.
SEF652Y
4. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171 detected? Is it difficult to start engine?
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch ªOFFº.
3. Disconnect mass air flow sensor harness connector, and restart and run engine for at least 3 seconds at idle speed.
SEF995W
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure diagnostic trouble code No. 0100 is displayed in Diagnostic Test Mode II.
6. Erase the diagnostic test mode II (Self-diagnostic results) memory. Refer to ªHow to Erase Emission-related Diagnostic
Informationº, EC-QG-44.
7. Make sure diagnostic trouble code No. 0000 is displayed in Diagnostic Test Mode II.
8. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC 0171 detected? Is it difficult to start engine?
YesorNo
Ye s©Perform trouble diagnosis for DTC P0171. Refer to EC-QG-208.
No©GO TO 3.
DTC P0138 HEATED OXYGEN SENSOR 2 (REAR)
(MAX. VOLTAGE MONITORING)QG16I18DE
Diagnostic Procedure (Cont'd)
EC-185
Component DescriptionNLEC0162The heated oxygen sensor 2 (rear), after three way catalyst, moni-
tors the oxygen level in the exhaust gas.
Even if switching characteristics of the heated oxygen sensor 1
(front) are shifted, the air fuel ratio is controlled to stoichiometric,
by the signal from the heated oxygen sensor 2 (rear).
This sensor is made of ceramic zirconia. The zirconia generates
voltage from approximately 1V in richer conditions to 0V in leaner
conditions.
Under normal conditions the heated oxygen sensor 2 (rear) is not
used for engine control operation.
CONSULT-II Reference Value in Data Monitor
Mode
NLEC0163Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 (B1)
IEngine: After warming upRevving engine from idle to 3,000
rpm0 - 0.3V+,Approx. 0.6 - 1.0V
HO2S2 MNTR
(B1)LEAN+,RICH
ECM Terminals and Reference ValueNLEC0164Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
63 LHeated oxygen sensor 2
(rear)[Engine is running]
IAfter warming up to normal operating temperature
and revving engine from idle to 2,000 rpm0 - Approximately 1.0V
On Board Diagnosis LogicNLEC0165The heated oxygen sensor 2 (rear) has a much longer switching
time between rich and lean than the heated oxygen sensor 1
(front). The oxygen storage capacity before the three way catalyst
causes the longer switching time. To judge the malfunctions of
heated oxygen sensor 2 (rear), ECM monitors whether the switch-
ing response of the sensor's voltage is faster than specified during
various driving conditions such as fuel-cut.
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0139
0139IIt takes more than the specified time for the sensor to
respond between rich and lean.IHarness or connectors
(The sensor circuit is open or shorted.)
IHeated oxygen sensor 2 (rear)
IFuel pressure
IInjectors
IIntake air leaks
SEF327R
SEF302U
DTC P0139 HEATED OXYGEN SENSOR 2 (REAR)
(RESPONSE MONITORING)QG16I18DE
Component Description
EC-188
2 CLEAR THE SELF-LEARNING DATA
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªSELF-LEARN CONTROLº in ªWORK SUPPORTº mode with CONSULT-II.
3. Clear the self-learning control coefficient by touching ªSTARTº.
SEF652Y
4. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0172 detected? Is it difficult to start engine?
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch ªOFFº.
3. Disconnect mass air flow sensor harness connector, and restart and run engine for at least 3 seconds at idle speed.
SEF995W
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure diagnostic trouble code No. 0100 is displayed in Diagnostic Test Mode II.
6. Erase the diagnostic test mode II (Self-diagnostic results) memory. Refer to ªHow to Erase Emission-related Diagnostic
Informationº, EC-QG-44.
7. Make sure diagnostic trouble code No. 0000 is displayed in Diagnostic Test Mode II.
8. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC 0172 detected? Is it difficult to start engine?
YesorNo
Ye s©Perform trouble diagnosis for DTC P0172. Refer to EC-QG-215.
No©GO TO 3.
DTC P0139 HEATED OXYGEN SENSOR 2 (REAR)
(RESPONSE MONITORING)QG16I18DE
Diagnostic Procedure (Cont'd)
EC-193
Component DescriptionNLEC0171The heated oxygen sensor 2 (rear), after three way catalyst, moni-
tors the oxygen level in the exhaust gas.
Even if switching characteristics of the heated oxygen sensor 1
(front) are shifted, the air fuel ratio is controlled to stoichiometric,
by the signal from the heated oxygen sensor 2 (rear).
This sensor is made of ceramic zirconia. The zirconia generates
voltage from approximately 1V in richer conditions to 0V in leaner
conditions.
Under normal conditions the heated oxygen sensor 2 (rear) is not
used for engine control operation.
CONSULT-II Reference Value in Data Monitor
Mode
NLEC0172Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 (B1)
IEngine: After warming upRevving engine from idle to 3,000
rpm0 - 0.3V+,Approx. 0.6 - 1.0V
HO2S2 MNTR
(B1)LEAN+,RICH
ECM Terminals and Reference ValueNLEC0173Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
63 LHeated oxygen sensor 2
(rear)[Engine is running]
IAfter warming up to normal operating temperature
and revving engine from idle to 2,000 rpm0 - Approximately 1.0V
On Board Diagnosis LogicNLEC0174The heated oxygen sensor 2 (rear) has a much longer switching
time between rich and lean than the heated oxygen sensor 1
(front). The oxygen storage capacity before the three way catalyst
causes the longer switching time. To judge the malfunctions of
heated oxygen sensor 2 (rear), ECM monitors whether or not the
voltage is too high during various driving conditions such as fuel-
cut.
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0140
0140IAn excessively high voltage from the sensor is sent to
ECM.IHarness or connectors
(The sensor circuit is open or shorted.)
IHeated oxygen sensor 2 (rear)
SEF327R
SEF305U
DTC P0140 HEATED OXYGEN SENSOR 2 (REAR)
(HIGH VOLTAGE)QG16I18DE
Component Description
EC-197
DescriptionNLEC0180SYSTEM DESCRIPTIONNLEC0180S01
Sensor Input Signal to ECMECM func-
tionActuator
Camshaft position sensor (PHASE)
Crankshaft position sensor (POS)Engine speedHeated
oxygen
sensor 2
heater
(rear) con-
trolHeated oxygen sensor 2 heater
(rear)
The ECM performs ON/OFF control of the heated oxygen sensor 2 heater (rear) corresponding to the engine
speed.
OPERATIONNLEC0180S02
Engine condition Heated oxygen sensor 2 heater (rear)
Engine stopped OFF
Engine is running. After driving for 2 minutes at a speed
of 70 km/h (43 MPH) or moreON
Engine speed above 3,600 rpm OFF
CONSULT-II Reference Value in Data Monitor
Mode
NLEC0181Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 HTR (B1)IEngine speedBelow 3,600 rpm [After driving for 2 minutes at a
speed of 70 km/h (43 MPH) or more]ON
Above 3,600 rpm OFF
IIgnition switch ON (Engine stopped) OFF
ECM Terminals and Reference ValueNLEC0182Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
3 W/RHeated oxygen sensor 2
heater (rear)[Engine is running]
IEngine speed is below 3,600 rpm [After driving
for 2 minutes at a speed of 70 km/h (43 MPH) or
more]Approximately 0.7V
[Engine is running]
IEngine speed is above 3,600 rpm
BATTERY VOLTAGE
(11 - 14V)
[Ignition switch ªONº]
IEngine stopped
DTC P0141 HEATED OXYGEN SENSOR 2 HEATER
(REAR)QG16I18DE
Description
EC-203
On Board Diagnosis LogicNCEC0188With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from the Heated oxygen sensor 1 (front).
The ECM calculates the necessary compensation to correct the offset between the actual and the theoretical
ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MI (2 trip detection logic).
Sensor Input Signal to ECMECM func-
tionActuator
Heated oxygen sensor 1 (front)Density of oxygen in exhaust gas
(Mixture ratio feedback signal)Fuel injec-
tion & mix-
ture ratio
controlInjectors
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0171
0171IFuel injection system does not operate properly.
IThe amount of mixture ratio compensation is too large.
(The mixture ratio is too lean.)IIntake air leaks
IHeated oxygen sensor 1 (front)
IInjectors
IExhaust gas leaks
IIncorrect fuel pressure
ILack of fuel
IMass air flow sensor
DTC Confirmation ProcedureNCEC0189NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Turn ignition switch ªONº and select ªSELF-LEARNING CONTº
in ªWORK SUPPORTº mode with CONSULT-II.
4) Clear the self-learning control coefficient by touching ªCLEARº.
5) Select ªDATA MONITORº mode with CONSULT-II.
6) Start engine again and let it idle for at least 10 minutes.
The 1st trip DTC P0171 should be detected at this stage, if a
malfunction exists. If so, go to ªDiagnostic Procedureº, EC-QG-
211.
7) If it is difficult to start engine at step 6, the fuel injection sys-
tem has a malfunction.
8) Crank engine while depressing accelerator pedal. If engine
starts, go to ªDiagnostic Procedureº, EC-QG-211. If engine
does not start, visually check for exhaust and intake air leak.
With GST
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Disconnect mass air flow sensor harness connector. Then
restart and run engine for at least 3 seconds at idle speed.
4) Stop engine and reconnect mass air flow sensor harness con-
nector.
5) Select ªMODE 7º with GST. Make sure 1st trip DTC P0100 is
detected.
6) Select ªMODE 4º with GST and erase the 1st trip DTC P0100.
SEF652Y
NEF068A
SEF995W
DTC P0171 FUEL INJECTION SYSTEM FUNCTION
(LEAN SIDE)QG16I18DE
On Board Diagnosis Logic
EC-208
On Board Diagnosis LogicNCEC0192With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from the Heated oxygen sensor 1 (front).
The ECM calculates the necessary compensation to correct the offset between the actual and the theoretical
ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too rich.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MI (2 trip detection logic).
Sensor Input Signal to ECMECM func-
tionActuator
Heated oxygen sensor 1 (front)Density of oxygen in exhaust gas
(Mixture ratio feedback signal)Fuel injec-
tion & mix-
ture ratio
controlInjectors
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0172
0172IFuel injection system does not operate properly.
IThe amount of mixture ratio compensation is too large.
(The mixture ratio is too rich.)IHeated oxygen sensor 1 (front)
IInjectors
IExhaust gas leaks
IIncorrect fuel pressure
IMass air flow sensor
DTC Confirmation ProcedureNCEC0193NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Turn ignition switch ªONº and select ªSELF-LEARN CON-
TROLº in ªWORK SUPPORTº mode with CONSULT-II.
4) Clear the self-learning control coefficient by touching ªCLEARº.
5) Select ªDATA MONITORº mode with CONSULT-II.
6) Start engine again and let it idle for at least 10 minutes.
The 1st trip DTC P0172 should be detected at this stage, if a
malfunction exists. If so, go to ªDiagnostic Procedureº, EC-QG-
218.
7) If it is difficult to start engine at step 6, the fuel injection sys-
tem has a malfunction.
8) Crank engine while depressing accelerator pedal. If engine
starts, go to ªDiagnostic Procedureº, EC-QG-218. If engine
does not start, remove ignition plugs and check for fouling, etc.
With GST
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Disconnect mass air flow sensor harness connector. Then
restart and run engine for at least 3 seconds at idle speed.
4) Stop engine and reconnect mass air flow sensor harness con-
nector.
5) Select ªMODE 7º with GST. Make sure 1st trip DTC P0100 is
detected.
6) Select ªMODE 4º with GST and erase the 1st trip DTC P0100.
SEF652Y
NEF068A
SEF995W
DTC P0172 FUEL INJECTION SYSTEM FUNCTION
(RICH SIDE)QG16I18DE
On Board Diagnosis Logic
EC-215