2011 INFINITI QX56 ignition

P0137, P0157 HO2S2EC-247
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
NO >> GO TO 6.
3.CHECK HEATED OXYGEN SENSOR 2-I
Without CONSULT-III
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 4.
4.CHECK HEATED OXYGEN SENSOR 2-II
Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 5.
5.CHECK HEATED OXYGEN SENSOR 2-III
Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 6.
ECM
Condition Voltage
Connector +–
Te r m i n a l Te r m i n a l
F110 96
[HO2S2
(bank 1)] 100Revving up to 4,000 rpm under no load at
least 10 times The voltage should be above 0.74 V at
least once during this procedure.
The voltage should be below 0.18 V at
least once during this procedure.
87
[HO2S2
(bank 2)]
ECM
Condition Voltage
Connector +–
Te r m i n a l Te r m i n a l
F110 96
[HO2S2
(bank 1)] 100 Keeping engine at idle for 10 minutes The voltage should be above 0.74 V at
least once during this procedure.
The voltage should be below 0.18 V at
least once during this procedure.
87
[HO2S2
(bank 2)]
ECM
Condition Voltage
Connector +–
Te r m i n a l Te r m i n a l
F110 96
[HO2S2
(bank 1)] 100Coasting from 80 km/h (50 MPH) with se-
lector lever in the D position The voltage should be above 0.74 V at
least once during this procedure.
The voltage should be below 0.18 V at
least once during this procedure.
87
[HO2S2
(bank 2)]
Revision: 2010 May2011 QX56

EC-250
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0138, P0158 HO2S2
1.PRECONDITIONING
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
6. Let engine idle for 2 minutes.
7. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-251, "Diagnosis Procedure".
NO-1 >> With CONSULT-III: GO TO 3.
NO-2 >> With GST: GO TO 5.
3.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B
WITH CONSULT-III
NOTE:
For better results, perform “DTC WORK SU PPORT” at a temperature of 0 to 30°C (32 to 86 °F).
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
6. Let engine idle for 1 minute.
7. Select “DATA MONITOR” mode with CONSULT-III.
8. Check that “COOLAN TEMP/S” indicates more than 70 °C (158 °F).
If not, warm up engine and go to next step when “COOLAN TEMP/S” indication reaches 70°C (158 °F).
9. Open engine hood.
10. Select “HO2S2 (B1) P1146” (for DTC P0138) or “HO2S2 (B2) P1166” (for DTC P0158) of “HO2S2” in
“DTC WORK SUPPORT” mode with CONSULT-III.
11. Follow the instruction of CONSULT-III display. NOTE:
It will take at most 10 minutes until “COMPLETED” is displayed.
12. Touch “SELF-DIAG RESULTS”.
Which is displayed on CONSULT-III screen?
OK >> INSPECTION END
NG >> Go to EC-251, "
Diagnosis Procedure".
CON NOT BE DIAGNOSED>>GO TO 4.
4.PERFORM DTC CONFIRMATION PROC EDURE FOR MALFUNCTION B AGAIN
1. Turn ignition switch OFF and leave the vehi cle in a cool place (soak the vehicle).
2. Perform DTC confirmation procedure again.
>> GO TO 3.
5.PERFORM COMPONENT FUNCTION CHECK FOR MALFUNCTION B
WITH GST
Perform component function check. Refer to EC-251, "
Component Function Check".
NOTE:
Use component function check to check the overall func tion of the heated oxygen sensor 2 circuit. During this
check, a 1st trip DTC might not be confirmed.
Is the inspection result normal?
Revision: 2010 May2011 QX56

P0138, P0158 HO2S2EC-251
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
YES >> INSPECTION END
NO >> Go to
EC-251, "
Diagnosis Procedure".
Component Function CheckINFOID:0000000006217818
1.PERFORM COMPONENT FUNCTION CHECK-I
WITH GST
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
6. Let engine idle for 1 minute.
7. Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 2.
2.PERFORM COMPONENT FUNCTION CHECK-II
Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 3.
3.PERFORM COMPONENT FUNCTION CHECK-III
Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Go to EC-251, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000006217819
1.INSPECTION START
Confirm the detected malfunction (A or B). Refer to EC-249, "
DTC Logic".
DTCECM
Condition Voltage
Connector +–
Terminal Terminal
P0138 F110 96
100Revving up to 4,000 rpm under no load at
least 10 times The voltage should be below 0.18 V at
least once during this procedure.
P0158 87
DTC ECM
Condition Voltage
Connector +–
Terminal Terminal
P0138 F110 96
100 Keeping engine at idle for 10 minutes The voltage should be below 0.18 V at
least once during this procedure.
P0158 87
DTC ECM
Condition Voltage
Connector +–
Terminal Terminal
P0138 F110 96
100Coasting from 80 km/h (50 MPH) with se-
lector lever in the D position The voltage should be below 0.18 V at
least once during this procedure.
P0158 87
Revision: 2010 May2011 QX56

P0138, P0158 HO2S2EC-253
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
 Discard any heated oxygen sensor which has been dr
opped from a height of more than 0.5 m (19.7
in) onto a hard surface such as a concrete floor; use a new one.
 Before installing new oxygen sensor, clean exh aust system threads using Oxygen Sensor Thread
Cleaner [commercial service tool (J-43897-18 or J-43897-12)] and approved anti-seize lubricant
(commercial service tool).
>> INSPECTION END
7.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
>> INSPECTION END
8.CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE
1. Clear the mixture ratio self-learning value. Refer to EC-152, "
Work Procedure".
2. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0172 or P0175 detected? Is it difficult to start engine?
YES >> Perform trouble diagnosis for DTC P0172, P0175. Refer to EC-267, "DTC Logic".
NO >> GO TO 9.
9.CHECK HEATED OXYGEN SENSOR 2 GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.
3. Disconnect ECM harness connector.
4. Check the continuity between HO2S2 harness connector and ECM harness connector.
5. Also check harness for short to ground and short to power.
Is the inspection result normal?
YES >> GO TO 10.
NO >> Repair open circuit, short to ground or short to power in harness or connectors.
10.CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check the continuity between HO2S2 harness connector and ECM harness connector.
2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and
ground.
3. Also check harness for short to power.
Is the inspection result normal?
YES >> GO TO 11.
NO >> Repair open circuit, short to ground or short to power in harness or connectors.
DTC HO2S2 ECM
Continuity
Bank Connector Terminal Connector Terminal
P0138 1 F87 1 F110 100 Existed
P0158 2 F88 1
DTC HO2S2 ECM
Continuity
Bank Connector Terminal Connector Terminal
P0138 1 F87 4 F11096
Existed
P0158 2 F88 4 87
DTC HO2S2 ECM
Ground Continuity
Bank Connector Terminal Connector Terminal
P0138 1 F87 4 F11096
Ground Not existed
P0158 2 F88 4 87
Revision: 2010 May2011 QX56

P0138, P0158 HO2S2EC-255
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Start engine and keep the engine speed between 3,500 and
4,000 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 4.
4.CHECK HEATED OXYGEN SENSOR 2-II
Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 5.
5.CHECK HEATED OXYGEN SENSOR 2-III
Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 6.
6.REPLACE HEATED OXYGEN SENSOR 2
Replace malfunctioning heated oxygen sensor 2. Refer to EM-40, "
Exploded View".
CAUTION:
 Discard any heated oxygen sensor which has been dr opped from a height of more than 0.5 m (19.7
in) onto a hard surface such as a concrete floor; use a new one.
ECM
Condition Voltage
Connector +–
Te r m i n a l Te r m i n a l
F110 96
[HO2S2
(bank 1)] 100Revving up to 4,000 rpm under no load at
least 10 times The voltage should be above 0.74 V at
least once during this procedure.
The voltage should be below 0.18 V at
least once during this procedure.
87
[HO2S2
(bank 2)]
ECM
Condition Voltage
Connector +–
Te r m i n a l Te r m i n a l
F110 96
[HO2S2
(bank 1)] 100 Keeping engine at idle for 10 minutes The voltage should be above 0.74 V at
least once during this procedure.
The voltage should be below 0.18 V at
least once during this procedure.
87
[HO2S2
(bank 2)]
ECM
Condition Voltage
Connector +–
Te r m i n a l Te r m i n a l
F110 96
[HO2S2
(bank 1)] 100Coasting from 80 km/h (50 MPH) with se-
lector lever in the D position The voltage should be above 0.74 V at
least once during this procedure.
The voltage should be below 0.18 V at
least once during this procedure.
87
[HO2S2
(bank 2)]
Revision: 2010 May2011 QX56

P0139, P0159 HO2S2EC-257
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P0139, P0159 HO2S2
DTC LogicINFOID:0000000006217821
DTC DETECTION LOGIC
The heated oxygen sensor 2 has a much longer switching time
between rich and lean than the air fuel
ratio (A/F) sensor 1. The oxy-
gen storage capacity of the three way catalyst (manifold) causes the
longer switching time. To judge the malfunctions of heated oxygen
sensor 2, ECM monitors whether the switching response of the sen-
sor's voltage is faster than specified during various driving conditions
such as fuel cut.
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
Will CONSULT-III be used?
YES >> GO TO 2.
NO >> GO TO 4.
2.PERFORM DTC CONFIRMATION PROCEDURE
WITH CONSULT-III
TESTING CONDITION:
For better results, perform “DTC WORK SUPPORT” at a temperature of 0 to 30 °C (32 to 86 °F).
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Restart engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
6. Let engine idle for 1 minute.
7. Select “DATA MONITOR” mode with CONSULT-III.
8. Check that “COOLAN TEMP/S” indicates more than 70 °C (158 °F).
If not, warm up engine and go to next step when “COOLAN TEMP/S” indication reaches to 70°C (158 °F).
9. Open engine hood.
10. Select “HO2S2 (B1) P0139” or “HO2S2 (B2) P 0159” of “HO2S2” in “DTC WORK SUPPORT” mode with
CONSULT-III.
11. Start engine and follow the instruction of CONSULT-III display.
NOTE:
It will take at most 10 minutes until “COMPLETED” is displayed.
12. Touch “SELF-DIAG RESULTS”.
SEF302U
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0139 HO2S2 (B1)
[Heated oxygen sensor 2
(bank 1) circuit slow response] It takes more time for the sensor to respond
between rich and lean than the specified
time.  Harness or connectors
(The heated oxygen sensor 2 circuit is
open or shorted)
 Heated oxygen sensor 2
 Fuel pressure
 Fuel injector
 Intake air leaks
P0159
HO2S2 (B2)
[Heated oxygen sensor 2
(bank 2) circuit slow response]
Revision: 2010 May2011 QX56

EC-258
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0139, P0159 HO2S2
Which is displayed on CONSULT-III screen?
OK >> INSPECTION END
NG >> Go to
EC-259, "
Diagnosis Procedure".
CAN NOT BE DIAGNOSED>>GO TO 3.
3.PERFORM DTC CONFIRMATION PROCEDURE AGAIN
1. Turn ignition switch OFF and leave the vehi cle in a cool place (soak the vehicle).
2. Perform DTC confirmation procedure again.
>> GO TO 2.
4.PERFORM COMPONENT FUNCTION CHECK
WITH GST
Perform component function check. Refer to EC-258, "
Component Function Check".
NOTE:
Use component function check to check the overall func tion of the heated oxygen sensor 2 circuit. During this
check, a 1st trip DTC might not be confirmed.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Go to EC-259, "
Diagnosis Procedure".
Component Function CheckINFOID:0000000006217822
1.PERFORM COMPONENT FUNCTION CHECK-I
WITH GST
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Restart engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
6. Let engine idle for 1 minute.
7. Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 2.
2.PERFORM COMPONENT FUNCTION CHECK-II
Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 3.
DTC ECM
Condition Voltage
Connector +–
Terminal Terminal
P0139 F110 96
100Revving up to 4,000 rpm under no load at
least 10 times A change of voltage should be more than
0.24 V for 1 second during this procedure.
P0159 87
DTC ECM
Condition Voltage
Connector +–
Terminal Terminal
P0139 F110 96
100 Keeping engine at idle for 10 minutes A change of voltage should be more than
0.24 V for 1 second during this procedure.
P0159 87
Revision: 2010 May2011 QX56

P0139, P0159 HO2S2EC-259
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
3.PERFORM COMPONENT FUNCTION CHECK-III
Check the voltage between ECM harness connector terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Go to EC-259, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000006217823
1.CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE
1. Clear the mixture ratio self-learning value. Refer to EC-152, "
Work Procedure".
2. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171, P0172, P0174 or P 0175 detected? Is it difficult to start engine?
YES >> Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to EC-263, "DTC Logic"
or EC-267, "DTC Logic".
NO >> GO TO 2.
2.CHECK HEATED OXYGEN SENSOR 2 GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.
3. Disconnect ECM harness connector.
4. Check the continuity between HO2S2 harness connector and ECM harness connector.
5. Also check harness for short to ground and short to power.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair open circuit, short to ground or short to power in harness or connectors.
3.CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check the continuity between HO2S2 harness connector and ECM harness connector.
2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and
ground.
DTC ECM
Condition Voltage
Connector +–
Terminal Terminal
P0139 F110 96
100Coasting from 80 km/h (50 MPH) with se-
lector lever in the D position A change of voltage should be more than
0.24 V for 1 second during this procedure.
P0159 87
DTC HO2S2 ECM
Continuity
Bank Connector Terminal Connector Terminal
P0139 1 F87 1 F110 100 Existed
P0159 2 F88 1
DTC HO2S2 ECM
Continuity
Bank Connector Terminal Connector Terminal
P0139 1 F87 4 F11096
Existed
P0159 2 F88 4 87
DTC HO2S2 ECM
Ground Continuity
Bank Connector Terminal Connector Terminal
P0139 1 F87 4 F11096
Ground Not existed
P0159 2 F88 4 87
Revision: 2010 May2011 QX56