2011 INFINITI QX56 service

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

EC-254
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0138, P0158 HO2S2
11 .CHECK HEATED OXYGEN SENSOR 2
Refer to EC-254, "
Component Inspection (HO2 sensor 2)".
Is the inspection result normal?
YES >> GO TO 13.
NO >> GO TO 12.
12.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 dropped 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
13.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
>> INSPECTION END
Component Inspection (HO2 sensor 2)INFOID:0000000006217820
1.INSPECTION START
Will CONSULT-III be used?
Will CONSULT-III be used?
YES >> GO TO 2.
NO >> GO TO 3.
2.CHECK HEATED OXYGEN SENSOR 2
WITH CONSULT-III
1. Start engine and warm it up to the normal operating temperature.
2. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
3. Let engine idle for 1 minute.
4. Select “FUEL INJECTION” in “ACT IVE TEST” mode, and select “HO2S2 (B1)/(B2)” as the monitor item
with CONSULT-III.
5. Check “HO2S2 (B1)/(B2)” at idle speed when adjusting “FUEL INJECTION” to ±25%.
“HO2S2 (B1)/(B2)” should be above 0.74 V at least once when the “FUEL INJECTION” is +25%.
“HO2S2 (B1)/(B2)” should be below 0.18 V at least once when the “FUEL INJECTION” is −25%.
Is the inspection result normal?
YES >> INSPECTION END
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.
JMBIA1573GB
Revision: 2010 May2011 QX56

EC-256
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0138, P0158 HO2S2
 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
Revision: 2010 May2011 QX56

EC-260
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0139, P0159 HO2S2
3. Also check harness for short to power.
Is the inspection result normal?
YES >> GO TO 4.
NO >> Repair open circuit, short to ground or short to power in harness or connectors.
4.CHECK HEATED OXYGEN SENSOR 2
Refer to EC-260, "
Component Inspection (HO2 sensor 2)".
Is the inspection result normal?
YES >> GO TO 6.
NO >> GO TO 5.
5.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 dropped 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
6.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
>> INSPECTION END
Component Inspection (HO2 sensor 2)INFOID:0000000006217824
1.INSPECTION START
Will CONSULT-III be used?
Will CONSULT-III be used?
YES >> GO TO 2.
NO >> GO TO 3.
2.CHECK HEATED OXYGEN SENSOR 2
WITH CONSULT-III
1. Start engine and warm it up to the normal operating temperature.
2. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
3. Let engine idle for 1 minute.
4. Select “FUEL INJECTION” in “ACT IVE TEST” mode, and select “HO2S2 (B1)/(B2)” as the monitor item
with CONSULT-III.
5. Check “HO2S2 (B1)/(B2)” at idle speed when adjusting “FUEL INJECTION” to ±25%.
“HO2S2 (B1)/(B2)” should be above 0.74 V at least once when the “FUEL INJECTION” is +25%.
“HO2S2 (B1)/(B2)” should be below 0.18 V at least once when the “FUEL INJECTION” is −25%.
Is the inspection result normal?
YES >> INSPECTION END
JMBIA1573GB
Revision: 2010 May2011 QX56

EC-262
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0139, P0159 HO2S2
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 dropped 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
Revision: 2010 May2011 QX56

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
EC-265
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
5. Check the continuity between
A/F sensor 1 harness connector and ground, or ECM harness connector
and ground.
6. Also check harness for short to power.
Is the inspection result normal?
YES >> GO TO 4.
NO >> Repair open circuit, short to ground or short to power in harness or connectors.
4.CHECK FUEL PRESSURE
Check fuel pressure. Refer to EC-153, "
Work Procedure".
Is the inspection result normal?
YES >> GO TO 6.
NO >> GO TO 5.
5. DETECT MALFUNCTIONING PART
Check fuel hoses and fuel tubes for clogging.
Is the inspection result normal?
YES >> Replace “fuel filter and fuel pump assembly”. Refer to FL-5, "Removal and Installation".
NO >> Repair or replace malfunctioning part.
6.CHECK MASS AIR FLOW SENSOR
WITH CONSULT-III
1. Install all removed parts.
2. Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT-III.
For specification, refer to EC-538, "
Mass Air Flow Sensor".
WITH GST
1. Install all removed parts.
2. Check mass air flow sensor signal in Service $01 with GST.
For specification, refer to EC-538, "
Mass Air Flow Sensor".
Is the measurement value within the specification?
YES >> GO TO 7.
NO >> Check connectors for rusted terminals or loose c onnections in the mass air flow sensor circuit or
grounds. Refer to EC-201, "
Diagnosis Procedure".
7.CHECK FUNCTION OF FUEL INJECTOR
DTC A/F sensor 1 ECM
Continuity
Bank Connector Terminal Connector Terminal
P0171 1 F67 3
F110 88
Existed
490
694
P0174 2 F68 378
480
674
DTC A/F sensor 1 ECM
Continuity Continuity
Bank Connector Terminal Connector Terminal
P0171 1 F67 3
F110 88
Existed Not existed
490
694
P0174 2 F68 378
480
674
Revision: 2010 May2011 QX56

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
EC-269
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
5. Check the continuity between
A/F sensor 1 harness connector and ground, or ECM harness connector
and ground.
6. Also check harness for short to power.
Is the inspection result normal?
YES >> GO TO 4.
NO >> Repair open circuit, short to ground or short to power in harness or connectors.
4.CHECK FUEL PRESSURE
Check fuel pressure. Refer to EC-153, "
Work Procedure".
Is the inspection result normal?
YES >> GO TO 5.
NO >> Replace fuel filter and fuel pump assembly”. Refer to FL-5, "
Removal and Installation".
5.CHECK MASS AIR FLOW SENSOR
WITH CONSULT-III
1. Install all removed parts.
2. Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT-III. For specification, refer to EC-538, "
Mass Air Flow Sensor".
WITH GST
1. Install all removed parts.
2. Check mass air flow sensor signal in “Service $01” with GST. For specification, refer to EC-538, "
Mass Air Flow Sensor".
Is the measurement value within the specification?
YES >> GO TO 6.
NO >> Check connectors for rusted terminals or loose c onnections in the mass air flow sensor circuit or
grounds. Refer to EC-201, "
Diagnosis Procedure".
6.CHECK FUNCTION OF FUEL INJECTOR
WITH CONSULT-III
1. Start engine.
2. Perform “POWER BALANCE” in “A CTIVE TEST” mode with CONSULT-III.
3. Check that each circuit produces a momentary engine speed drop.
WITHOUT CONSULT-III
1. Start engine and let it idle.
DTC A/F sensor 1 ECM
Continuity
Bank Connector Terminal Connector Terminal
P0171 1 F67 3
F110 88
Existed
490
694
P0174 2 F68 378
480
674
DTC A/F sensor 1 ECM
Continuity Continuity
Bank Connector Terminal Connector Terminal
P0171 1 F67 3
F110 88
Existed Not existed
490
694
P0174 2 F68 378
480
674
Revision: 2010 May2011 QX56

EC-296
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0300, P0301, P0302, P
0303, P0304, P0305, P0306, P0307, P0308 MISFIRE
4. Also check harness for short to power.
Is the inspection result normal?
YES >> GO TO 16.
NO >> Repair open circuit, short to ground or short to power in harness or connectors.
16.CHECK A/F SENSOR 1 HEATER
Refer to EC-182, "
Component Inspection (A/F Sensor 1 Heater)".
Is the inspection result normal?
YES >> GO TO 17.
NO >> Replace malfunctioning A/F sensor 1. Refer to EX-5, "
Exploded View".
17.CHECK MASS AIR FLOW SENSOR
WITH CONSULT-III
Check mass air flow sensor signal in “DATA MONITOR” mode with CONSULT-III.
For specification, refer to EC-538, "
Mass Air Flow Sensor".
WITH GST
Check mass air flow sensor signal in Service $01 with GST.
For specification, refer to EC-538, "
Mass Air Flow Sensor".
Is the measurement value within the specification?
YES >> GO TO 18.
NO >> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
ground. Refer to EC-201, "
Diagnosis Procedure".
18.CHECK SYMPTOM MATRIX CHART
Check items on the rough idle symptom in EC-524, "
Symptom Table".
Is the inspection result normal?
YES >> GO TO 19.
NO >> Repair or replace malfunctioning part.
19.ERASE THE 1ST TRIP DTC
Some tests may cause a 1st trip DTC to be set.
Erase the 1st trip DTC from the ECM memo ry after performing the tests. Refer to EC-63, "
CONSULT-III
Function" or EC-60, "On Board Diagnosis Function".
>> GO TO 20.
20.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
>> INSPECTION END
DTC A/F sensor 1 ECM
Continuity
Bank Connector Terminal Connector Terminal
P0130 1 F67 6 F11094
Existed
P0150 2 F68 6 74
Revision: 2010 May2011 QX56