2011 INFINITI QX56 ignition

P0139, P0159 HO2S2EC-261
< 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

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
EC-263
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P0171, P0174 FUEL INJE
CTION SYSTEM FUNCTION
DTC LogicINFOID:0000000006217825
DTC DETECTION LOGIC
With 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 f eedback signal from A/F sensor 1. The ECM calculates
the necessary compensation to co rrect the offset between the actual and the theoretical ratios.
In case the amount of the compensation value is extrem ely large (the actual mixture ratio is too lean), the
ECM judges the condition as the fuel injection system malfunction and illuminates the MIL (2 trip 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-I
1. Clear the mixture ratio self-learning value. Refer to EC-152, "
Work Procedure".
2. Start engine.
Is it difficult to start engine?
YES >> GO TO 3.
NO >> GO TO 4.
3.RESTART ENGINE
If it is difficult to start engine, the f uel injection system has a malfunction, too.
Crank engine while depressing accelerator pedal.
NOTE:
When depressing accelerator pedal three fourths (3/4) or more, the control system does not start the engine.
Do not depress accelerator pedal too much.
Does engine start?
YES >> Proceed to EC-264, "Diagnosis Procedure".
NO >> Check exhaust and intake air leakage visually.
4.PERFORM DTC CONFIRMATION PROCEDURE-II
1. Keep engine idle for at least 5 minutes.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-264, "Diagnosis Procedure".
Sensor Input signal to ECM ECM function Actuator
A/F sensor 1 Density of oxygen in exhaust gas
(Mixture ratio feedback signal) Fuel injection control Fuel injector
DTC No.Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0171 FUEL SYS-LEAN-B1
[Fuel injection system too
lean (bank 1)]
 Fuel injection system does not operate properly.
 The amount of mixture ratio compensation is too
large. (The mixture ratio is too lean.)  Intake air leakage
 A/F sensor 1
 Fuel injector
 Exhaust gas leakage
 Incorrect fuel pressure
 Lack of fuel
 Mass air flow sensor
 Incorrect PCV hose connection
P0174
FUEL SYS-LEAN-B2
[Fuel injection system too
lean (bank 2)]
Revision: 2010 May2011 QX56

EC-264
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0171, P0174 FUEL INJECTION SYSTEM FUNCTION
NO >> GO TO 5.
5.PERFORM DTC CONFIRMATION PROCEDURE-III
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.
4. Start engine.
5. Maintain the following conditions for at least 10 consecutive minutes. Hold the accelerator pedal as steady as possible.
CAUTION:
Always drive vehicle at a safe speed.
6. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-264, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217826
1.CHECK EXHAUST GAS LEAKAGE
1. Start engine and run it at idle.
2. Listen for an exhaust gas leakage before three way catalyst (manifold).
Is exhaust gas leakage detected?
YES >> Repair or replace malfunctioning part.
NO >> GO TO 2.
2.CHECK FOR INTAKE AIR LEAKAGE
1. Listen for an intake air leakage after the mass air flow sensor.
2. Check PCV hose connection.
Is intake air leakage detected?
YES >> Repair or replace malfunctioning part.
NO >> GO TO 3.
3.CHECK A/F SENSOR 1 CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.
Vehicle speed 50 - 120 km/h (31 - 75 MPH)
PBIB1216E
Revision: 2010 May2011 QX56

P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
EC-267
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P0172, P0175 FUEL INJE
CTION SYSTEM FUNCTION
DTC LogicINFOID:0000000006217827
DTC DETECTION LOGIC
With 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 f eedback signal from A/F sensor 1. The ECM calculates
the necessary compensation to co rrect 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 malfunc tion and illuminates the MIL (2 trip 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-I
1. Clear the mixture ratio self-learning value. Refer to EC-152, "
Work Procedure".
2. Start engine.
Is it difficult to start engine?
YES >> GO TO 3.
NO >> GO TO 4.
3.RESTART ENGINE
If it is difficult to start engine, the f uel injection system has a malfunction, too.
Crank engine while depressing accelerator pedal.
NOTE:
When depressing accelerator pedal three fourths (3/4) or more, the control system does not start the engine.
Do not depress accelerator pedal too much.
Does engine start?
YES >> Proceed to EC-268, "Diagnosis Procedure".
NO >> Remove spark plugs and check for fouling, etc.
4.PERFORM DTC CONFIRMATION PROCEDURE-II
1. Keep engine idle for at least 5 minutes.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-268, "Diagnosis Procedure".
NO >> GO TO 5.
Sensor Input signal to ECM ECM function Actuator
A/F sensor 1 Density of oxygen in exhaust gas
(Mixture ratio feedback signal) Fuel injection control Fuel injector
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0172 FUEL SYS-RICH-B1
[Fuel injection system too
rich (bank 1)]
 Fuel injection system does not operate properly.
 The amount of mixture ratio compensation is too
large. (The mixture ratio is too rich.)  A/F sensor 1
 Fuel injector
 Exhaust gas leakage
 Incorrect fuel pressure
 Mass air flow sensor
P0175 FUEL SYS-RICH-B2
[Fuel injection system too
rich (bank 2)]
Revision: 2010 May2011 QX56

EC-268
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P0172, P0175 FUEL INJECTION SYSTEM FUNCTION
5.PERFORM DTC CONFIRMATION PROCEDURE-III
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.
4. Start engine.
5. Maintain the following conditions for at least 10 consecutive minutes. Hold the accelerator pedal as steady as possible.
CAUTION:
Always drive vehicle at a safe speed.
6. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-268, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217828
1.CHECK EXHAUST GAS LEAKAGE
1. Start engine and run it at idle.
2. Listen for an exhaust gas leakage before three way catalyst (manifold).
Is exhaust gas leakage detected?
YES >> Repair or replace malfunctioning part.
NO >> GO TO 2.
2.CHECK FOR INTAKE AIR LEAKAGE
Listen for an intake air leakage after the mass air flow sensor.
Is intake air leakage detected?
YES >> Repair or replace malfunctioning part.
NO >> GO TO 3.
3.CHECK A/F SENSOR 1 CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.
Vehicle speed 50 - 120 km/h (31 - 75 MPH)
PBIB1216E
Revision: 2010 May2011 QX56

P0181 FTT SENSOREC-271
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P0181 FTT SENSOR
DTC LogicINFOID:0000000006288289
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-I
1. Turn ignition switch ON and wait at least 10 seconds.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-271, "Diagnosis Procedure".
NO >> GO TO 3.
3.CHECK ENGINE COOLANT TEMPERATURE
WITH CONSULT-III
1. Select “COOLAN TEMP/S” in “DATA MONITOR” with CONSULT-III.
2. Check “COOLAN TEMP/S” value.
WITH GST
Follow the procedure “With CONSULT-III” above.
“
COOLAN TEMP/S” less than 60°C (140°F)?
YES >> INSPECTION END
NO >> GO TO 4.
4.PERFORM DTC CONFIRMATION PROCEDURE-II
WITH CONSULT-III
1. Cool engine down until “COOLAN TEMP/S” is less than 60 °C (140 °F).
2. Wait at least 10 seconds.
3. Check 1st trip DTC.
WITH GST
Follow the procedure “With CONSULT-III” above.
Is 1st trip DTC detected?
YES >> Proceed to EC-271, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288290
1.CHECK DTC WITH COMBINATION METER
Refer to MWI-30, "
CONSULT-III Function".
Is the inspection result normal?
YES >> GO TO 2.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P0181 FTT SENSOR
[Fuel tank temperature sensor
circuit range/performance] Rationally incorrect voltage from the sensor
is sent to ECM, compared with the voltage
signals from engine coolant temperature sen-
sor and intake air temperature sensor.  Harness or connectors
(The FTT sensor circuit is open or
shorted)
 Fuel tank temperature sensor
 Combination meter
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

P0181 FTT SENSOREC-273
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
Component Inspection (Fuel
Tank Temperature Sensor)INFOID:0000000006288291
1.CHECK FUEL TANK TEMPERATURE SENSOR
1. Turn ignition switch OFF.
2. Disconnect “fuel level sensor unit and fuel pump” harness connector.
3. Remove fuel level sensor unit.
4. Check resistance between “fuel level sensor unit and fuel pump ” terminals by heating with hot water as shown in the figure.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Replace “fuel level sensor unit and fuel pump”.
Terminals Condition Resistance (k Ω)
4 and 5 Temperature [ °C ( °F)] 20 (68) 2.3 - 2.7
50 (122) 0.79 - 0.90
JMBIA0167ZZ
Revision: 2010 May2011 QX56