INFINITI QX56 2009 Factory Service Manual

EC-94
< COMPONENT DIAGNOSIS >[VK56DE]
P0031, P0032, P0051, P00
52 A/F SENSOR 1 HEATER
P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER
DescriptionINFOID:0000000003771338
SYSTEM DESCRIPTION
The ECM performs ON/OFF duty control of the A/F sensor 1 heater corresponding to the engine operating
condition to keep the temperature of A/F sensor 1 element at the specified range.
On Board Diagnosis LogicINFOID:0000000003771339
DTC Confirmation ProcedureINFOID:0000000003771340
NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next step.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
TESTING CONDITION:
Before performing the following pr ocedure, confirm that battery voltage is between 10.5V and 16V at
idle.
1. Start engine and let it idle for at least 10 seconds.
2. Check 1st trip DTC.
3. If 1st trip DTC is detected, go to EC-94, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771341
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Sensor Input Signal to ECM ECM function Actuator
Camshaft position sensor (PHASE)
Crankshaft position sensor (POS) Engine speed
Air fuel ratio (A/F) sensor 1
heater control Air fuel ratio (A/F) sensor 1
heater
Mass air flow sensor Amount of intake air
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0031
0031
(Bank 1) Air fuel ratio (A/F) sensor
1 heater control circuit low The current amperage in the air fuel ratio (A/F) sen-
sor 1 heater circuit is out of the normal range.
(An excessively low voltage signal is sent to ECM
through the air fuel ratio (A/F) sensor 1 heater.)  Harness or connectors
(The A/F sensor 1 heater circuit is
open or shorted.)
 A/F sensor 1 heater
P0051
0051
(Bank 2)
P0032
0032
(Bank 1)
Air fuel ratio (A/F) sensor
1 heater control circuit
high The current amperage in the air fuel ratio (A/F) sen-
sor 1 heater circuit is out of the normal range.
(An excessively high voltage signal is sent to ECM
through the air fuel ratio (A/F) sensor 1 heater.)  Harness or connectors
(The A/F sensor 1 heater circuit is
shorted.)
 A/F sensor 1 heater
P0052
0052
(Bank 2)
Revision: December 20092009 QX56

P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER
EC-95
< COMPONENT DIAGNOSIS > [VK56DE]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
Refer to
EC-85, "Ground Inspection".
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY CIRCUIT
1. Disconnect air fuel ratio (A /F) sensor 1 harness connector.
2. Turn ignition switch ON.
3. Check voltage between A/F sensor 1 terminal 4 and ground with CONSULT-III or tester.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
 Harness connectors E5, F14
 IPDM E/R harness connector E119
 15A fuse
 Harness for open or short between A/F sensor 1 and fuse
>> Repair or replace harness or connectors.
4.CHECK A/F SENSOR 1 HEATER OUTPUT SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 2 (bank 1) or 24, 43 (bank 2) and A/F sensor 1 terminal
3.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
BBIA0354E
Voltage: Battery voltage
BBIA0376E
PBIB3308E
Continuity should exist.
Revision: December 20092009 QX56

EC-96
< COMPONENT DIAGNOSIS >[VK56DE]
P0031, P0032, P0051, P00
52 A/F SENSOR 1 HEATER
OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK A/F SENSOR 1 HEATER
Refer to EC-96, "Component Inspection"
.
OK or NG
OK >> GO TO 6.
NG >> Replace malfunctioning air fuel ratio (A/F) sensor 1.
6.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "How to Check Terminal"
and GI-38, "Intermittent Incident".
>> INSPECTION END
Component InspectionINFOID:0000000003771342
AIR FUEL RATIO (A/F) SENSOR 1 HEATER
1. Check resistance between A/F sensor 1 terminals as follows.
2. If NG, replace air fuel ratio (A/F) sensor 1.
CAUTION:
 Discard any A/F 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 A/F sensor, clean exhaust system threads using Heated Oxygen Se nsor Thread Cleaner tool J-
43897-18 or J-43897-12 and approved anti-seize lubricant.
Terminal No. Resistance
3 and 4 1.98 - 2.66 Ω [at 25 °C (77 °F)]
3 and 1, 2 ∞ Ω
(Continuity should not exist)
4 and 1, 2
PBIB3309E
Revision: December 20092009 QX56

P0037, P0038, P0057, P0058 HO2S2 HEATER
EC-97
< COMPONENT DIAGNOSIS > [VK56DE]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P0037, P0038, P0057, P0058 HO2S2 HEATER
DescriptionINFOID:0000000003771343
SYSTEM DESCRIPTION
The ECM performs ON/OFF control of the heated o
xygen sensor 2 heater corresponding to the engine speed,
amount of intake air and engine coolant temperature.
OPERATION
On Board Diagnosis LogicINFOID:0000000003771344
DTC Confirmation ProcedureINFOID:0000000003771345
NOTE:
If DTC Confirmation Procedure has been previously conduc ted, always perform the following before conduct-
ing the next step.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
TESTING CONDITION:
Before performing the following procedure, confi rm that battery voltage is between 10.5V and 16V at
idle.
1. Turn ignition switch ON and select “DATA MONITOR” mode with CONSULT-III.
2. Start engine and warm it up to the normal operating temperature.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Start the engine and keep the engine speed between 3,500 rpm and 4,000 rpm for at least 1 minute under no load.
5. Let engine idle for 1 minute.
Sensor Input signal to ECM ECM function Actuator
Camshaft position sensor (PHASE)
Crankshaft position sensor (POS) Engine speed
Heated oxygen sensor 2
heater controlHeated oxygen sensor 2 heater
Engine coolant temperature sensor Engine coolant temperature
Mass air flow sensor Amount of intake air
Engine speed (rpm) Heated oxygen sensor 2 heater
Above 3,600 OFF
Below 3,600 rpm after the following conditions are met.
 Engine: After warming up
 Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and at idle for 1 minute under no load ON
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0037
0037
(Bank 1) Heated oxygen sensor 2
heater control circuit low The current amperage in the heated oxygen sen-
sor 2 heater circuit is out of the normal range.
(An excessively low voltage signal is sent to ECM
through the heated oxygen sensor 2 heater.)  Harness or connectors
(The heated oxygen sensor 2 heater
circuit is open or shorted.)
 Heated oxygen sensor 2 heater
P0057
0057
(Bank 2)
P0038
0038
(Bank 1)
Heated oxygen sensor 2
heater control circuit high The current amperage in the heated oxygen sen-
sor 2 heater circuit is out of the normal range.
(An excessively high voltage signal is sent to ECM
through the heated oxygen sensor 2 heater.)  Harness or connectors
(The heated oxygen sensor 2 heater
circuit is shorted.)
 Heated oxygen sensor 2 heater
P0058
0058
(Bank 2)
Revision: December 20092009 QX56

EC-98
< COMPONENT DIAGNOSIS >[VK56DE]
P0037, P0038, P0057,
P0058 HO2S2 HEATER
6. Check 1st trip DTC.
7. If 1st trip DTC is detected, go to EC-98, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771346
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to EC-85, "Ground Inspection"
.
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK HO2S2 POWER SUPPLY CIRCUIT
1. Disconnect heated oxygen sensor 2 harness connector.
2. Turn ignition switch ON.
3. Check voltage between HO2S2 terminal 3 and ground with CONSULT-III or tester.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
 Harness connectors E5, F14
 IPDM E/R harness connector E119
 15A fuse
 Harness for open or short between heated oxygen sensor 2 and fuse
>> Repair harness or connectors.
4.CHECK HO2S2 HEATER OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
BBIA0354E
BBIA0435E
Voltage: Battery voltage
PBIB0112E
Revision: December 20092009 QX56

P0037, P0038, P0057, P0058 HO2S2 HEATER
EC-99
< COMPONENT DIAGNOSIS > [VK56DE]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal and HO2S2 terminal as follows.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK HEATED OXYGEN SENSOR 2 HEATER
Refer to EC-99, "Component Inspection"
.
OK or NG
OK >> GO TO 6.
NG >> Replace malfunctioning heated oxygen sensor 2.
6.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "How to Check Terminal"
and GI-38, "Intermittent Incident".
>> INSPECTION END
Component InspectionINFOID:0000000003771347
HEATED OXYGEN SENSOR 2 HEATER
1. Check resistance between HO2S2 terminals as follows.
2. If NG, replace heated oxygen sensor 2.
CAUTION:
 Discard any heated oxygen sen sor 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 exhaust system
threads using Oxygen Sensor Thread Cleaner tool J-43897-18
or J-43897-12 and approved anti-seize lubricant.
DTCTe r m i n a l s
Bank
ECM Sensor
P0037, P0038 6 2 1
P0057, P0058 25 2 2
Continuity should exist.
Terminal No. Resistance 2 and 3 8 - 10 Ω [at 25 °C (77 °F)]
1 and 2, 3, 4 ∞ Ω
(Continuity should not exist)
4 and 1, 2, 3
SEF249Y
Revision: December 20092009 QX56

EC-100
< COMPONENT DIAGNOSIS >[VK56DE]
P0075, P0081 IVT CONTROL SOLENOID VALVE
P0075, P0081 IVT CONTROL SOLENOID VALVE
Component DescriptionINFOID:0000000003771348
Intake valve timing control solenoid valve is activated by ON/OFF
pulse duty (ratio) signals from the ECM.
The intake valve timing control solenoid valve changes the oil
amount and direction of flow through intake valve timing control unit
or stops oil flow.
The longer pulse width advances valve angle.
The shorter pulse width retards valve angle.
When ON and OFF pulse widths become equal, the solenoid valve
stops oil pressure flow to fix the intake valve angle at the control
position.
On Board Diagn
osis LogicINFOID:0000000003771349
DTC Confirmation ProcedureINFOID:0000000003771350
1. If DTC Confirmation Procedure has been previously conducted, always perform the following before con-
ducting the next step.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Turn ignition switch ON.
c. Turn ignition switch OFF and wait at least 10 seconds.
2. Start engine and let it idle for 5 seconds.
3. Check 1st trip DTC.
4. If 1st trip DTC is detected, go to EC-100, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771351
1.CHECK INTAKE VALVE TIMING CONTROL SOLENOID VALVE POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect intake valve timing control solenoid valve harness connector.
PBIB1842E
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0075
0075
(Bank 1) Intake valve timing control
solenoid valve circuit An improper voltage is sent to the ECM
through intake valve timing control solenoid
valve.  Harness or connectors
(Intake valve timing control solenoid valve
circuit is open or shorted.)
 Intake valve timing control solenoid valve
P0081
0081
(Bank 2)
BBIA0771E
Revision: December 20092009 QX56

P0075, P0081 IVT CONTROL SOLENOID VALVE
EC-101
< COMPONENT DIAGNOSIS > [VK56DE]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
3. Turn ignition switch ON.
4. Check voltage between intake valve timing control solenoid
valve terminal 2 and ground with CONSULT-III or tester.
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2.DETECT MALFUNCTIONING PART
Check the following.
 Harness connectors E2, F32
 IPDM E/R harness connector E119
 Harness for open or short between intake valve timing control solenoid valve and IPDM E/R
>> Repair open circuit or short to ground or short to power in harness or connectors.
3.CHECK INTAKE VALVE TIMING CONTROL SOLENO ID VALVE OUTPUT SIGNAL CIRCUIT FOR OPEN
AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between the following; ECM terminal 10 and intake valve timing control solenoid valve (Bank 1) terminal 1 or
ECM terminal 11 and intake valve timing control solenoid valve (Bank 2) terminal 1.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 4.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK INTAKE VALVE TIMING CONTROL SOLENOID VALVE
Refer to EC-101, "Component Inspection"
.
OK or NG
OK >> GO TO 5.
NG >> Replace malfunctioning intake valve timing control solenoid valve. Refer to EC-492
.
5.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "How to Check Terminal"
and GI-38, "Intermittent Incident".
>> INSPECTION END
Component InspectionINFOID:0000000003771352
INTAKE VALVE TIMING CONTROL SOLENOID VALVE
1. Disconnect intake valve timing control solenoid valve harness connector.
1. Intake valve timing control position
sensor (bank 2) 2. Intake valve timing control solenoid
valve (bank 2) 3. Drive belt
4. Radiator hose 5. Intake valve timing control solenoid valve (bank 1)6. Intake valve timing control position
sensor (bank 1)
Voltage: Battery voltage
PBIB0351E
Continuity should exist.
Revision: December 20092009 QX56

EC-102
< COMPONENT DIAGNOSIS >[VK56DE]
P0075, P0081 IVT CONTROL SOLENOID VALVE
2. Check resistance between intake valve timing control solenoid
valve terminals as follows.
If NG, replace intake valve timing control solenoid valve. Refer to
EC-492
.
If OK, go to next step.
3. Remove intake valve timing control solenoid valve. Refer to EC-
492.
4. Provide 12V DC between intake valve timing control solenoid valve terminals and then interrupt it. Make sure that the plunger
moves as shown in the figure.
CAUTION:
Do not apply 12V DC continuo usly for 5 seconds or more.
Doing so may result in damage to the coil in intake valve
timing control solenoid valve.
If NG, replace intake valve timing control solenoid valve. Refer to
EC-492
.
NOTE:
Always replace O-ring when intake valve timing control
solenoid valve is removed.
Terminals Resistance
1 and 2 7.1 - 7.7 Ω [at 20 °C (68 °F)]
1 or 2 and ground ∞Ω
(Continuity should not exist)
MBIB0027E
PBIB2388E
Revision: December 20092009 QX56

P0101 MAF SENSOREC-103
< COMPONENT DIAGNOSIS > [VK56DE]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P0101 MAF SENSOR
Component DescriptionINFOID:0000000003771353
The mass air flow sensor is placed in
the stream of intake air. It mea-
sures the intake flow rate by measuring a part of the entire intake
flow. The mass air flow sensor c ontrols the temperature of the hot
wire to a certain amount. The heat generated by the hot wire is
reduced as the intake air flows around it. The more air, the greater
the heat loss.
Therefore, the electric current s upplied to the hot wire is changed to
maintain the temperature of the hot wire as air flow increases. The
ECM detects the air flow by means of this current change.
On Board Diagnosis LogicINFOID:0000000003771354
DTC Confirmation ProcedureINFOID:0000000003771355
Perform PROCEDURE FOR MALFUNCTION A first.
If the DTC cannot be confirmed, perform PROCEDURE FOR MALFUNCTION B.
NOTE:
If DTC Confirmation Procedure has been previously conduc ted, always perform the following before conduct-
ing the next step.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
PROCEDURE FOR MALFUNCTION A
NOTE:
If engine will not start or stops soon, wait at leas t 10 seconds with engine stopped (Ignition switch ON) instead
of running engine at idle speed.
1. Start engine and warm it up to normal operating temperature.
2. Run engine for at least 10 seconds at idle speed.
3. Check 1st trip DTC.
4. If 1st trip DTC is detected, go to EC-105, "Diagnosis Procedure"
.
PROCEDURE FOR MALFUNCTION B
CAUTION:
Always drive vehicle at a safe speed.
With CONSULT-III
BBIA0355E
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0101
0101 Mass air flow sensor circuit
range/performance A)
A high voltage from the sensor is sent to ECM
under light load driving condition.  Harness or connectors
(The sensor circuit is open or
shorted.)
 Mass air flow sensor
 EVAP control system pressure sensor
 Intake air temperature sensor
B) A low voltage from the sensor is sent to ECM
under heavy load driving condition.  Harness or connectors
(The sensor circuit is open or
shorted.)
 Intake air leaks
 Mass air flow sensor
 EVAP control system pressure sensor
 Intake air temperature sensor
Revision: December 20092009 QX56