2011 INFINITI QX56 Fuel

EC-408
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1421 COLD START CONTROL
P1421 COLD START CONTROL
DescriptionINFOID:0000000006288263
ECM controls ignition timing and engine idle speed when engine is started with prewarming up condition.
This control promotes the activation of three way ca
talyst by heating the catalyst and reduces emissions.
DTC LogicINFOID:0000000006288264
DTC DETECTION LOGIC
NOTE:
If DTC P1421 is displayed with other DTC, firs t perform the trouble diagnosis for other DTC.
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.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11 V at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Select “DATA MONITOR” mode with CONSULT-III.
4. Check the indication of “COOLAN TEMP/S”. If it is between 7 °C (45 °F) and 36 °C (97 °F), go to the following steps.
If it is below 7 °C (45 °F), warm engine up to more than 7 °C (45 °F) and retry from step 1.
If it is above 36 °C (97 °F), cool engine down to less than 36 °C (97 °F) and retry from step 1.
5. Start engine and let it idle for 5 minutes.
6. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-408, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288265
1.PERFORM IDLE AIR VOLUME LEARNING
Perform EC-148, "
Work Procedure".
Is Idle Air Volume Learning carried out successfully?
YES >> GO TO 2.
NO >> Follow the instruction of Idle Air Volume Learning.
2.CHECK INTAKE SYSTEM
Check for the cause of intake air volume lacking. Refer to the following.
 Crushed intake air passage
 Intake air passage clogging
Is the inspection result normal?
YES >> GO TO 3.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1421 Cold start emission reduction
strategy monitoring ECM does not control ignition timing and engine
idle speed properly when engine is started with
prewarming up condition.  Lack of intake air volume
 Fuel injection system
ECM
Revision: 2010 May2011 QX56

P1421 COLD START CONTROLEC-409
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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NO >> Repair or replace malfunctioning part
3.CHECK FUEL INJECTION SYSTEM FUNCTION
Perform DTC Confirmation Procedure for DTC P0171, P0174. Refer to EC-263, "
DTC Logic".
Is the inspection result normal?
YES >> GO TO 4.
NO >> Go to EC-264, "
Diagnosis Procedure" for DTC P0171, P0174.
4.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Erase DTC.
3. Perform DTC Confirmation Procedure.
See EC-408, "
DTC Logic".
Is the 1st trip DTC P1421 displayed again?
YES >> GO TO 5.
NO >> INSPECTION END
5.REPLACE ECM
1. Replace ECM.
2. Go to EC-143, "
Work Procedure".
>> INSPECTION END
Revision: 2010 May2011 QX56

EC-410
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1423, P1424 COLD
START CONTROL
P1423, P1424 COLD START CONTROL
DescriptionINFOID:0000000006288266
ECM controls fuel injection timing and fuel injection quantity when engine is started with the engine cold.
This control promotes the activation of three way ca talyst by heating the catalyst and reduces emissions.
DTC LogicINFOID:0000000006288267
DTC DETECTION LOGIC
NOTE:
If DTC P1423 or P1424 is displayed with other DTC, first perform the trouble diagnosis for other DTC.
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
WITH CONSULT-III
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Select “DATA MONITOR” mode with CONSULT-III.
4. Check that “COOLAN TEMP/S”.
- If it is between 5 °C (41 °F) and 40 °C (104 °F) go to the following steps.
- If it is below 5 °C (41 °F) warm engine up to more than 5 °C (41 °F) and retry from step 1.
- If it is above 40 °C (104 °F) cool engine down to less than 40 °C (104 °F) and retry from step 1.
5. Start engine and let it idle for 5 minutes.
6. Check 1st trip DTC.
WITH GST
Follow the procedure “With CONSULT-III” above.
Is 1st trip DTC detected?
YES >> Proceed to EC-410, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288268
1.INSPECTION START
1. Turn ignition switch ON.
2. Erase DTC.
3. Perform DTC confirmation procedure. Refer to EC-410, "
DTC Logic".
4. Check 1st trip DTC.
Is the 1st trip DTC P1423 or P1424 displayed again?
YES >> GO TO 2.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1423 COLD START CONTROL
(Cold start emission reduction
strategy monitoring) ECM does not control fuel injection timing prop-
erly when engine is started with the engine cold.
ECM
P1424 COLD START CONTROL
(Cold start emission reduction
strategy monitoring) ECM does not control fuel injection quantity
properly when engine is started with with the en-
gine cold.
Revision: 2010 May2011 QX56

P2539, P2541, P2542 LOW FUEL PRESSURE SENSOR
EC-483
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P2539, P2541, P2542 LOW
FUEL PRESSURE SENSOR
DTC LogicINFOID:0000000006288355
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.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is 11 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine and let it idle for at least 60 seconds.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Proceed to EC-483, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288356
1.CHECK LOW FUEL PRESSURE SENSOR POWER SUPPLY-I
1. Turn ignition switch OFF.
2. Disconnect low fuel pressure sensor connector.
3. Turn ignition switch ON.
4. Check the voltage between low fuel pressure sensor harness connector terminals.
Inspection result normal?
YES >> GO TO 6.
NO >> GO TO 2.
2.CHECK LOW FUEL PRESSURE SENSOR POWER SUPPLY-II
Check the voltage between low fuel pressure sensor harness connector and the ground.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P2539 LOW FUEL PRES SEN
(Low fuel pressure sensor
circuit low input and high in-
put) Signal voltage from the low fuel pressure
sensor remains at more than 4.84 V / less
than 0.3 V for 5 seconds or more.  Harness or connectors
(Low fuel pressure sensor circuit is open
or shorted.)
(Power steering pressure sensor circuit is
open or shorted.)
(Cooling fan speed sensor circuit is open
or shorted.)
(FRP sensor circuit is open or shorted.)
 Low fuel pressure sensor
 Power steering pressure sensor
 Cooling fan speed sensor
 FRP sensor
P2541
LOW FUEL PRES SEN
(Low fuel pressure sensor
circuit low input) Signal voltage from the low fuel pressure
sensor remains at less than 0.49 V for 5 sec-
onds or more.
P2542 LOW FUEL PRES SEN
(Low fuel pressure sensor
circuit high input) Signal voltage from the low fuel pressure
sensor remains at more than 4.1 V for 5 sec-
onds or more.
Low fuel pressure sensor
Vo l ta g e
(Approx.)
Connector +
−
terminal
F25 3 1 5 V
Revision: 2010 May2011 QX56

EC-484
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P2539, P2541, P2542 LOW
FUEL PRESSURE SENSOR
Is inspection result normal?
YES >> GO TO 4.
NO >> GO TO 3.
3.CHECK SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness connector for short to power and short to ground, between the following terminals.
Is inspection result normal?
YES >> Perform the trouble diagnosis for power supply circuit. Refer to EC-168, "Diagnosis Procedure".
NO >> Repair or replace error-detected parts.
4.CHECK LOW FUEL PRESSURE SENSOR GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check the continuity between low fuel pressu re sensor harness connector and ECM harness connector.
Is inspection result normal?
YES >> GO TO 5.
NO >> Repair or replace error-detected parts.
5.CHECK ECM GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check the continuity between ECM harness connector and the ground.
Is inspection result normal?
YES >> Check intermittent incident. Refer to GI-40, "Intermittent Incident".
+
−Voltag e
(Approx.)
Low fuel pressure sensor
Connector Terminal F25 3 Ground 5 V
ECM Sensor
Connector Terminal Name Connector Terminal
F 111 27Power steering pressure sensor F35 1
Low fuel pressure sensor F25 3
Cooling fan speed sensor F39 2
28 FRP sensor F26 1
+ −
Continuity
Low fuel pressure sensor ECM
Connector Terminal Connector Terminal F25 1 F111 45 Existed
ECM Ground Continuity
Connector Terminal
F 111 5
Ground Existed
E80 11 4
11 5
174
175
Revision: 2010 May2011 QX56

P2539, P2541, P2542 LOW FUEL PRESSURE SENSOR
EC-485
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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NO >> Repair or replace error-detected parts.
6.CHECK LOW FUEL PRESSURE SENSOR SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check the continuity between low fuel pressu re sensor harness connector and ECM harness connector.
4. Also check harness for short to ground and to power.
Is inspection result normal?
YES >> GO TO 7.
NO >> Repair or replace error-detected parts.
7.CHECK LOW FUEL PRESSURE SENSOR
Refer to EC-485, "
Component Inspection".
Is inspection result normal?
YES >> Check intermittent incident. Refer to GI-40, "Intermittent Incident".
NO >> Replace low fuel pressure sensor.
Component InspectionINFOID:0000000006289706
1.CHECK LOW FUEL PRESSURE SENSOR
WITH CONSULT-III
1. Turn ignition switch OFF.
2. Reconnect harness connector disconnected.
3. Start the engine.
4. Select “DATA MONITOR” mode with CONSULT-III.
5. Check that the “L/FUEL PRES SEN V” value.
WITHOUT CONSULT-III
1. Turn ignition switch OFF.
2. Reconnect harness connector disconnected.
3. Start the engine.
4. Check low fuel pressure sensor signal voltage.
+ −
Continuity
Low fuel pressure sensor ECM
Connector Terminal Connector Terminal F25 2 F111 23 Existed
Data monitor item Condition Va l u e
(Approx.)
L/FUEL PRES SEN V Engine speed: idle
3,000 –3,300 mV
Engine speed: 3,000 rpm (no load)
Revision: 2010 May2011 QX56

EC-486
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P2539, P2541, P2542 LOW
FUEL PRESSURE SENSOR
Is the inspection result normal?
YES >> INSPECTION END.
NO >> Replace low fuel pressure sensor. Refer to EM-43, "
Removal and Installation".
+−
Condition Va l u e
(Approx.)
Low fuel pressure sensor
Ground
Connector Terminal
F25 2 Ground [Engine is running]
 Warm-up condition
 Idle speed
[Engine is running]
 Warm-up condition
 Engine speed: 2,000 rpm
JPBIA3357ZZ
JPBIA3358ZZ
Revision: 2010 May2011 QX56

P2A00, P2A03 A/F SENSOR 1EC-487
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P2A00, P2A03 A/F SENSOR 1
DTC LogicINFOID:0000000006217987
DTC DETECTION LOGIC
To judge the malfunction, the A/F signal computed by ECM fr
om the A/F sensor 1 signal is monitored so it will
not shift to LEAN side or RICH side.
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.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is 11 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Clear the mixture ratio self-learning value. Refer to EC-152, "
Work Procedure".
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 1 minute under no load.
6. Let engine idle for 1 minute.
7. Keep engine speed between 2,500 and 3,000 rpm for 20 minutes.
8. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-487, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217988
1.RETIGHTEN A/F SENSOR 1
Loosen and retighten the A/F sensor 1. Refer to EX-5, "
Exploded View".
>> GO TO 2.
2.CHECK A/F SENSOR 1 CONNECTOR
1. Disconnect A/F sensor 1 harness connector.
2. Check that water is not inside connectors.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace harness connector.
3.CHECK FOR INTAKE AIR LEAKAGE
1. Reconnect A/F sensor 1 harness connector.
2. Start engine and run it at idle.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P2A00 A/F SENSOR1 (B1)
(Air fuel ratio (A/F) sensor 1 (bank 1)
circuit range/performance)  The output voltage computed by ECM from
the A/F sensor 1 signal shifts to the lean side
for a specified period.
 The A/F signal computed by ECM from the
A/F sensor 1 signal shifts to the rich side for
a specified period.  A/F sensor 1
 A/F sensor 1 heater
 Fuel pressure
 Fuel injector
 Intake air leaks
P2A03 A/F SENSOR1 (B2)
(Air fuel ratio (A/F) sensor 1 (bank 2)
circuit range/performance)
Revision: 2010 May2011 QX56