Diagnostic ProcedureNJEC0169
1 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
JEF104Y
©GO TO 2.
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.
SEF215Z
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 5 seconds at idle speed.
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure 1st trip DTC P0100 is displayed.
6. Erase the 1st trip DTC memory. Refer to ªHow to Erase Emission-related Diagnostic Informationº, EC-70.
7. Make sure DTC P0000 is displayed.
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-305.
No©GO TO 3.
DTC P0139 HEATED OXYGEN SENSOR 2 (REAR)
(RESPONSE MONITORING)
QG
Diagnostic Procedure
EC-280
SEF189Y
DTC Confirmation ProcedureNJEC0175NOTE:
If ªDTC Confirmation Procedure º has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
1) Turn ignition switch ªONº and select ªDATA MONITORº mode
with CONSULT-II.
2) Start engine and drive vehicle at a speed of more than 70 km/h
(43 MPH) for 2 consecutive minutes.
3) Stop vehicle with engine running.
4) Let engine idle for 1 minute.
5) Maintain the following conditions for at least 5 consecutive
minutes.
ENG SPEED Above 1,500 rpm
Selector lever Suitable position
6) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-288.
SEF032X
Overall Function CheckNJEC0176Use this procedure to check the overall function of the heated oxy-
gen sensor 2 (rear) circuit. During this check, a 1st trip DTC might
not be confirmed.
Without CONSULT-II
1) Start engine and drive vehicle at a speed of more than 70 km/h
(43 MPH) for 2 consecutive minutes.
2) Stop vehicle with engine running.
3) Set voltmeter probes between ECM terminals 63 (HO2S2 sig-
nal) and engine ground.
4) Check the voltage after revving up to 4,000 rpm under no load
at least 10 times.
(Depress and release accelerator pedal as soon as possible.)
The voltage should be below 2V during this procedure.
5) If NG, go to ªDiagnostic Procedureº, EC-288.
DTC P0140 HEATED OXYGEN SENSOR 2 (REAR) (HIGH VOLTAGE)QG
DTC Confirmation Procedure
EC-285
Diagnostic ProcedureNJEC0178
1 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
JEF104Y
©GO TO 2.
2 CHECK INPUT SIGNAL CIRCUIT
1. Disconnect heated oxygen sensor 2 (rear) harness connector and ECM harness connector.
SEF160Z
2. Check harness continuity between ECM terminal 63 and heated oxygen sensor 2 (rear) harness connector terminal 1.
Refer to wiring diagram.
Continuity should exist.
3. Check harness continuity between ECM terminal 63 [or heated oxygen sensor 2 (rear) harness connector terminal 1]
and ground.
Continuity should not exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 4.
NG©GO TO 3.
3 DETECT MALFUNCTIONING PART
Check the harness for open or short between heated oxygen sensor 2 (rear) and ECM.
©Repair open circuit or short to ground or short to power in harness or connectors.
DTC P0140 HEATED OXYGEN SENSOR 2 (REAR) (HIGH VOLTAGE)QG
Diagnostic Procedure
EC-288
DescriptionNJEC0180SYSTEM DESCRIPTIONNJEC0180S01
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.
OPERATIONNJEC0180S02
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
NJEC0181Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 HTR (B1)+Engine 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
+Ignition switch ON (Engine stopped) OFF
ECM Terminals and Reference ValueNJEC0182Specification 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]
+Engine 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]
+Engine speed is above 3,600 rpm
BATTERY VOLTAGE
(11 - 14V)
[Ignition switch ªONº]
+Engine stopped
DTC P0141 HEATED OXYGEN SENSOR 2 HEATER (REAR)QG
Description
EC-291
On Board Diagnosis LogicNJEC0183
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0141
0141+The current amperage in the heated oxygen sensor 2
heater (rear) circuit is out of the normal range.
[An improper voltage drop signal is sent to ECM through
the heated oxygen sensor 2 heater (rear).]+Harness or connectors
(The heated oxygen sensor 2 heater (rear) cir-
cuit is open or shorted.)
+Heated oxygen sensor 2 heater (rear)
DTC Confirmation ProcedureNJEC0184NOTE:
If ªDTC Confirmation Procedure º has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that bat-
tery voltage is in between 10.5V and 16V at idle.
SEF175Y
With CONSULT-II
1) Turn ignition switch ªONº and select ªDATA MONITORº mode
with CONSULT-II.
2) Start engine and drive vehicle at a speed of more than 70 km/h
(43 MPH) for 2 consecutive minutes. Engine speed must be
maintained at speeds of 3,600 rpm or less during vehicle
operations.
3) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-295.
With GST
1) Start engine and drive vehicle at a speed of more than 70 km/h
(43 MPH) for 2 consecutive minutes. Engine speed must be
maintained at speeds of 3,600 rpm or less during vehicle
operations.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Start engine and drive vehicle at a speed of more than 70 km/h
(43 MPH) for 2 consecutive minutes.
4) Select ªMODE 3º with GST.
5) If DTC is detected, go to ªDiagnostic Procedureº, EC-295.
When using GST, ªDTC Confirmation Procedure º should be
performed twice as much as when using CONSULT-II because
GST cannot display MODE 7 (1st trip DTC) concerning this
diagnosis. Therefore, using CONSULT-II is recommended.
DTC P0141 HEATED OXYGEN SENSOR 2 HEATER (REAR)QG
On Board Diagnosis Logic
EC-292
Diagnostic ProcedureNJEC0186
1 CHECK POWER SUPPLY
1. Turn ignition switch ªOFFº.
2. Disconnect heated oxygen sensor 2 (rear) harness connector.
SEF160Z
3. Turn ignition switch ªONº.
4. Check voltage between terminal 2 and ground.
SEF218W
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the following.
+Harness connectors E75, F36
+Harness connectors M21, E106 (Sedan), M160, E175 or M169, F113 (Hatchback)
+Harness for open or short between heated oxygen sensor 2 (rear) and fuse
+10A fuse
©Repair harness or connectors.
3 CHECK GROUND CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between heated oxygen sensor 2 (rear) harness connector terminal 3 and ECM terminal 3.
Refer to wiring diagram.
Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 5.
NG©GO TO 4.
DTC P0141 HEATED OXYGEN SENSOR 2 HEATER (REAR)QG
Diagnostic Procedure
EC-295
On Board Diagnosis LogicNJEC0188With 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 MIL (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
0171+Fuel injection system does not operate properly.
+The amount of mixture ratio compensation is too large.
(The mixture ratio is too lean.)+Intake air leaks
+Heated oxygen sensor 1 (front)
+Injectors
+Exhaust gas leaks
+Incorrect fuel pressure
+Lack of fuel
+Mass air flow sensor
SEF215Z
SEF058Y
DTC Confirmation ProcedureNJEC0189NOTE:
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 ªSTARTº.
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-301.
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-301. If engine does
not start, visually check for exhaust and intake air leak.
JEF105Y
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.
DTC P0171 FUEL INJECTION SYSTEM FUNCTION (LEAN SIDE)QG
On Board Diagnosis Logic
EC-297
Diagnostic ProcedureNJEC0191
1 CHECK EXHAUST AIR LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust air leak before three way catalyst.
SEF099P
OK or NG
OK©GO TO 2.
NG©Repair or replace.
2 CHECK FOR INTAKE AIR LEAK
Listen for an intake air leak after the mass air flow sensor.
OK or NG
OK©GO TO 3.
NG©Repair or replace.
3 CHECK HEATED OXYGEN SENSOR 1 (FRONT) CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect heated oxygen sensor 1 (front) harness connector and ECM harness connector.
SEF012XA
3. Check harness continuity between ECM terminal 62 and heated oxygen sensor 1 (front) harness connector terminal 2.
Refer to wiring diagram.
Continuity should exist.
4. Check harness continuity between ECM terminal 62 [or heated oxygen sensor 1 (front) harness connector terminal 2]
and ground.
Continuity should not exist.
5. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 4.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
DTC P0171 FUEL INJECTION SYSTEM FUNCTION (LEAN SIDE)QG
Diagnostic Procedure
EC-301