2011 INFINITI QX56 ground

EC-252
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0138, P0158 HO2S2
Which malfunction is detected?
A>>GO TO 2
B>>GO TO 8.
2.CHECK HEATED OXYGEN SENSOR 2 CONNECTOR
1. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.
2. Check that water is not inside connectors.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace harness or connectors.
3.CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check the continuity between HO2S2 harness connector and ECM harness connector.
3. Also check harness for short to ground and 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 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 5.
NO >> Repair open circuit, short to ground or short to power in harness or connectors.
5.CHECK HEATED OXYGEN SENSOR 2
Refer to EC-254, "
Component Inspection (HO2 sensor 2)".
Is the inspection result normal?
YES >> GO TO 7.
NO >> GO TO 6.
6.REPLACE HEATED OXYGEN SENSOR 2
Replace malfunctioning heated oxygen sensor 2. Refer to EM-40, "
Exploded View".
CAUTION:
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-253
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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 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

P0139, P0159 HO2S2EC-259
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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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

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

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
EC-265
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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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]
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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-272
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0181 FTT SENSOR
NO >> Proceed to
MWI-69, "Component Function Check".
2.CHECK FUEL TANK TEMPERATURE SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect “fuel level sensor uni t and fuel pump” harness connector.
3. Turn ignition switch ON.
4. Check the voltage between “fuel level sensor unit and fuel pump” harness connector and ground.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
 Harness for open or short between ECM and “fuel level sensor unit and fuel pump”
 Loose or poor connection for each connector and harness
>> Repair open circuit, short to ground or short to power in harness or connector.
4.CHECK FUEL TANK TEMPERATURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect “combination meter” harness connector.
3. Check the continuity between “fuel level sensor unit and fuel pump” harness connector and “combination
meter” harness connector.
4. Also check harness for short to ground and short to power.
Is the inspection result normal?
YES >> GO TO 6.
NO >> GO TO 5.
5.DETECT MALFUNCTIONING PART
Check the following.
 Harness for open or short between “fuel level s ensor unit and fuel pump” and “combination meter”
 Loose or poor connection for each connector and harness
>> Repair open circuit, short to ground or short to power in harness or connector.
6.CHECK FUEL TANK TEMPERATURE SENSOR
Refer to EC-273, "
Component Inspection (Fuel Tank Temperature Sensor)".
Is the inspection result normal?
YES >> GO TO 7.
NO >> Replace fuel level sensor unit and fuel pump. Refer to FL-5, "
Removal and Installation".
7.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
>> INSPECTION END
Fuel level sensor unit and fuel pump Ground Voltage (V)
Connector Terminal
C5 4 Ground Approx. 5
Fuel level sensor unit and fuel pump Combination meter
Continuity
Connector Terminal Connector Terminal
C5 5 M34 24 Existed
Revision: 2010 May2011 QX56

EC-274
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0182, P0183 FTT SENSOR
P0182, P0183 FTT SENSOR
DTC LogicINFOID:0000000006288292
DTC DETECTION LOGIC
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.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON and wait at least 5 seconds.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-274, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288293
1.CHECK DTC WITH COMBINATION METER
Refer to MWI-30, "
CONSULT-III Function".
Is the inspection result normal?
YES >> GO TO 2.
NO >> Proceed to MWI-69, "
Component Function Check".
2.CHECK FUEL TANK TEMPERATURE SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect “fuel level sensor uni t and fuel pump” harness connector.
3. Turn ignition switch ON.
4. Check the voltage between “fuel level sensor unit and fuel pump” harness connector and ground.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
 Harness for open or short between ECM and “fuel level sensor unit and fuel pump”
DTC No.Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0182 FTT SEN/CIRCUIT
(Fuel tank temperature sen-
sor circuit low input) An excessively low voltage from the sensor is
sent to ECM.
 Harness or connectors
(The FTT sensor circuit is open or
shorted.)
 Fuel tank temperature sensor
 Combination meter
P0183 FTT SEN/CIRCUIT
(Fuel tank temperature sen-
sor circuit high input) An excessively high voltage from the sensor is
sent to ECM.
Fuel level sensor unit and
fuel pump Ground Voltage (V)
Connector Terminal
C5 4 Ground Approx. 5
Revision: 2010 May2011 QX56