Fuel sensor INFINITI QX56 2008 Factory Owner's Manual

EC-66
< FUNCTION DIAGNOSIS >[VK56DE]
ON BOARD DIAGNOSTIC (OBD) SYSTEM
*: This function is not necessary in the usual service procedure.
SELF-DIAG RESULTS MODE
Self Diagnostic Item
Regarding items of DTC and 1st trip DTC, refer to
EC-462, "DTC Index".
Freeze Frame Data and 1st Trip Freeze Frame Data
EVAP SYSTEM CLOSECLOSE THE EVAP CANISTER VENT CONTROL VALVE IN
ORDER TO MAKE EVAP SYSTEM CLOSE UNDER THE
FOLLOWING CONDITIONS.
• IGN SW ON
• ENGINE NOT RUNNING
• AMBIENT TEMPERATURE IS ABOVE 0° C (32°F).
• NO VACUUM AND NO HIGH PRESSURE IN EVAP SYS- TEM
• FUEL TANK TEMP. IS MORE THAN 0 °C (32 °F).
• WITHIN 10 MINUTES AFTER STARTING “EVAP SYS- TEM CLOSE”
• WHEN TRYING TO EXECUTE “EVAP SYSTEM CLOSE” UNDER THE CONDITION EXCEPT ABOVE, CONSULT-
III WILL DISCONTINUE IT AND DISPLAY APPROPRI-
ATE INSTRUCTION.
NOTE:
WHEN STARTING ENGINE, CONSULT-III MAY DIS-
PLAY “BATTERY VOLTAGE IS LOW. CHARGE BAT-
TERY”, EVEN IN USING CHARGED BATTERY. When detecting EVAP vapor leak
point of EVAP system
VIN REGISTRATION • IN THIS MODE, VIN IS REGISTERED IN ECMWhen registering VIN in ECM
TARGET IDLE RPM ADJ* • IDLE CONDITION When setting target idle speed
TARGET IGN TIM ADJ* • IDLE CONDITION When adjusting target ignition tim-
ing
WORK ITEM
CONDITION USAGE
Freeze frame data
item* Description
DIAG TROUBLE
CODE
[PXXXX] • The engine control co
mponent part/control system has a trouble code, it is displayed as PXXX X. (Refer to
EC-462, "
DTC Index".)
FUEL SYS-B1 • “Fuel injection system status” at the moment a malfunction is detected is displayed.
• One mode in the following is displayed. Mode2: Open loop due to detected system malfunction
Mode3: Open loop due to driving conditions (power enrichment, deceleration enleanment)
Mode4: Closed loop - using oxygen sensor(s) as feedback for fuel control
Mode5: Open loop - has not yet satisfied condition to go to closed loop
FUEL SYS-B2
CAL/LD VALUE [%] • The calculated load value at the moment a malfunction is detected is displayed.
COOLANT TEMP
[
° C] or [ °F] • The engine coolant temperature at the moment a malfunction is detected is displayed.
L-FUEL TRM-B1 [%] • “Long-term fuel trim” at the moment a malfunction is detected is displayed. • The long-term fuel trim indicates much more gradual feedback compensation to the base fuel schedule than short-term fuel trim.
L-FUEL TRM-B2 [%]
S-FUEL TRM-B1 [%] • “Short-term fuel trim” at the
moment a malfunction is detected is displayed.
• The short-term fuel trim indicates dynamic or instantaneous feedback compensation to the base fuel sched-
ule.
S-FUEL TRM-B2 [%]
ENGINE SPEED [rpm] • The engine speed at the moment a malfunction is detected is displayed.
VEHICL SPEED
[km/h] or [mph] • The vehicle speed at the moment a malfunction is detected is displayed.
ABSOL TH-P/S
[%] • The throttle valve opening at the moment a malfunction is detected is displayed.
B/FUEL SCHDL
[msec] • The base fuel schedule at the moment a malfunction is detected is displayed.
Revision: March 2010
2008 QX56

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*: The item is the same as that of 1st trip freeze frame data.
DATA MONITOR MODE
Monitored Item
×
: Applicable
INT/A TEMP SE
[° C] or [ °F] • The intake air temperature at the moment a malfunction is detected is displayed.
INT MANI PRES [kPa] These items are displayed but are not applicable to this model.
FTFMCH1 Freeze frame data
item* Description
Monitored item
[Unit] ECM IN-
PUT SIG- NALS MAIN
SIGNALS Description
Remarks
ENG SPEED [rpm] ×ו Indicates the engine speed computed
from the signal of the crankshaft position
sensor (POS) and camshaft position
sensor (PHASE). • Accuracy becomes poor if engine
speed drops below the idle rpm.
• If the signal is interrupted while the en- gine is running, an abnormal value may
be indicated.
MAS A/F SE-B1 [V] ×ו The signal voltage of the mass air flow
sensor is displayed. • When the engine is stopped, a certain
value is indicated.
• When engine is running specification
range is indicated in “SPEC”.
B/FUEL SCHDL
[msec] ו Base fuel schedule indicates the fuel in-
jection pulse width programmed into
ECM, prior to any learned on board cor-
rection. • When engine is running specification
range is indicated in “SPEC”.
A/F ALPHA-B1 [%] ×
• The mean value of the air-fuel ratio feed-back correction factor per cycle is indi-
cated. • When the engine is stopped, a certain
value is indicated.
• When engine is running specification
range is indicated in “SPEC”.
• This data also includes the data for the air-fuel ratio learning control.
A/F ALPHA-B2 [%]
×
COOLAN TEMP/S
[ ° C] or [ °F] ×× • The engine coolant temperature (deter-
mined by the signal voltage of the engine
coolant temperature sensor) is dis-
played. • When the engine coolant temperature
sensor is open or short-circuited, ECM
enters fail-safe mode. The engine cool-
ant temperature determined by the
ECM is displayed.
A/F SEN1 (B1) [V] ××
• The A/F signal computed from the input
signal of the A/F sensor 1 is displayed.
A/F SEN1 (B2) [V] ×
HO2S2 (B1) [V] ×
• The signal voltage of the heated oxygen
sensor 2 is displayed.
HO2S2 (B2) [V] ×
HO2S2 MNTR (B1)
[RICH/LEAN] ו Display of heated oxygen sensor 2 sig-
nal:
RICH: means the amount of oxygen after
three way catalyst is relatively small.
LEAN: means the amount of oxygen af-
ter three way catalyst is relatively large. • When the engine is stopped, a certain
value is indicated.
HO2S2 MNTR (B2)
[RICH/LEAN] ×
VHCL SPEED SE
[km/h] or [mph] ×ו The vehicle speed computed from the
vehicle speed signal sent from combina-
tion meter is displayed.
BATTERY VOLT [V] ×ו The power supply voltage of ECM is dis-
played.
ACCEL SEN 1 [V] ××
• The accelerator pedal position sensor
signal voltage is displayed. • ACCEL SEN 2 signal is converted by
ECM
in

ternally. Thus, it differs from
ECM terminal voltage signal.
ACCEL SEN 2 [V]
×
Revision: March 2010 2008 QX56

EC-68
< FUNCTION DIAGNOSIS >[VK56DE]
ON BOARD DIAGNOSTIC (OBD) SYSTEM
TP SEN 1-B1 [V]
××
• The throttle position sensor signal volt-
age is displayed. • TP SEN 2-B1 signal is converted by
ECM internally. Thus, it differs from
ECM terminal voltage signal.
TP SEN 2-B1 [V]
×
FUEL T/TMP SE
[ ° C] or [ °F] × • The fuel temperature (determined by the
signal voltage of the fuel tank tempera-
ture sensor) is displayed.
INT/A TEMP SE
[ ° C] or [ °F] ×× • The intake air temperature (determined
by the signal voltage of the intake air
temperature sensor) is indicated.
EVAP SYS PRES
[V] ×
• The signal voltage of EVAP control sys-
tem pressure sensor is displayed.
FUEL LEVEL SE [V] ו The signal voltage of the fuel level sen-
sor is displayed.
START SIGNAL
[ON/OFF] ×ו Indicates start signal status [ON/OFF]
computed by the ECM according to the
signals of engine speed and battery volt-
age. • After starting the engine, [OFF] is dis-
played regardless of the starter signal.
CLSD THL POS
[ON/OFF] ×ו Indicates idle position [ON/OFF] comput-
ed by ECM according to the accelerator
pedal position sensor signal.
AIR COND SIG
[ON/OFF] ×ו Indicates [ON/OFF] condition of the air
conditioner switch as determined by the
air conditioner signal.
P/N POSI SW
[ON/OFF] ××
• Indicates [ON/OFF] condition from the
park/neutral position (PNP) signal.
PW/ST SIGNAL
[ON/OFF] ×ו [ON/OFF] condition of the power steering
system (determined by the signal voltage
of the power steering pressure sensor
signal) is indicated.
LOAD SIGNAL [ON/
OFF] ×ו Indicates [ON/OFF] condition from the
electrical load signal.
ON: Rear window defogger switch is ON
and/or lighting switch is in 2nd position.
OFF: Both rear window defogger switch
and lighting switch are OFF.
IGNITION SW
[ON/OFF] ו Indicates [ON/OFF] condition from igni-
tion switch signal.
HEATER FAN SW
[ON/OFF] ×
• Indicates [ON/OFF] condition from heat-
er fan switch signal.
BRAKE SW
[ON/OFF] ו Indicates [ON/OFF] condition from the
stop lamp switch signal.
INJ PULSE-B1
[msec] ×
• Indicates the actual fuel injection pulse
width compensated by ECM according to
the input signals. • When the engine is stopped, a certain
computed value is indicated.
INJ PULSE-B2
[msec]
IGN TIMING [BT-
DC] ו
Ind
ic
ates the ignition timing computed by
ECM according to the input signals. • When the engine is stopped, a certain
value is indicated.
CAL/LD VALUE [%] • “Calculated load value” indicates the val-
ue of the current air flow divided by peak
air flow.
MASS AIRFLOW
[g·m/s] • Indicates the mass air flow computed by
ECM according to the signal voltage of
the mass air flow sensor.
Monitored item
[Unit] ECM IN-
PUT SIG-
NALS MAIN
SIGNALS Description
Remarks
Revision: March 2010 2008 QX56

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PURG VOL C/V [%]
• Indicates the EVAP canister purge vol-
ume control solenoid valve control value
computed by the ECM according to the
input signals.
• The opening becomes larger as the val- ue increases.
INT/V TIM (B1)
[ ° CA]
• Indicates [°CA] of intake camshaft ad-
vanced angle.
INT/V TIM (B2)
[ ° CA]
INT/V SOL (B1) [%] • The control value of the intake valve tim-
ing control solenoid valve (determined by
ECM according to the input signals) is in-
dicated.
• The advance angle becomes larger as
the value increases.
INT/V SOL (B2) [%]
AIR COND RLY
[ON/OFF]
ו The air conditioner relay control condi-
tion (determined by ECM according to
the input signals) is indicated.
FUEL PUMP RLY
[ON/OFF] ו Indicates the fuel pump relay control con-
dition determined by ECM according to
the input signals.
VENT CONT/V
[ON/OFF] • The control condition of the EVAP canis-
ter vent control valve (determined by
ECM according to the input signals) is in-
dicated.
ON: Closed
OFF: Open
THRTL RELAY [ON/
OFF] ו Indicates the throttle control motor relay
control condition determined by the ECM
according to the input signals.
COOLING FAN
[HI/OFF] ו The control condition of the cooling fan
(determined by ECM according to the in-
put signals) is indicated.
HI: High speed operation
OFF: Stop
HO2S2 HTR (B1)
[ON/OFF] • Indicates [ON/OFF] condition of heated
oxygen sensor 2 heater determined by
ECM according to the input signals.
HO2S2 HTR (B2)
[ON/OFF]
I/P PULLY SPD
[rpm] ו Indicates the engine speed computed
from the input speed sensor signal.
VEHICLE SPEED
[km/h] or [mph] ו Indicates the vehicle speed computed
from the output speed sensor signal.
IDL A/V LEARN
[YET/CMPLT] • Display the condition of idle air volume
learning
YET: Idle Air Volume Learning has not
been performed yet.
CMPLT: Idle Air Volume Learning has al-
ready been performed successfully.
TRVL AFTER MIL
[km] or [mile] • Distance traveled while MIL is activated.
Monitored item
[Unit] ECM IN-
PUT SIG-
NALS MAIN
SIGNALS Description
Remarks
Revision: March 2010 2008 QX56

ON BOARD DIAGNOSTIC (OBD) SYSTEMEC-71
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NOTE:
Any monitored item that does not match the vehicle being diagnosed is deleted from the display automatically.
ACTIVE TEST MODE
Test Item
ALT DUTY SIG
[ON/OFF] • The control condition of the power gener-
ation voltage variable control (deter-
mined by ECM according to the input
signals) is indicated.
ON: Power generation voltage variable
control is active.
OFF: Power generation voltage variable
control is inactive.
A/F ADJ-B1 • Indicates the correction factor stored in
ECM. The factor is calculated from the
difference between the target air/fuel ra-
tio stored in ECM and the air-fuel ratio
calculated from air fuel ratio (A/F) sensor
1 signal.
A/F ADJ-B2
Voltage [V]
• Voltage, frequency, duty cycle or pulse width measured by the probe. • Only # is displayed if item is unable to
be measured.
• Figures with #s are temporary ones. They are the same figures as an actual
piece of data which was just previously
measured.
Frequency [msec],
[Hz] or [%]
DUTY-HI
DUTY-LOW
PLS WIDTH-HI
PLS WIDTH-LOW Monitored item
[Unit] ECM IN-
PUT SIG-
NALS MAIN
SIGNALS Description
Remarks
TEST ITEMCONDITION JUDGEMENTCHECK ITEM (REMEDY)
FUEL INJEC-
TION • Engine: Return to the original
trouble condition
• Change the amount of fuel injec- tion using CONSULT-III. If trouble symptom disappears, see
CHECK ITEM.
• Harness and connectors
• Fuel injector
• Air fuel ratio (A/F) sensor 1
IGNITION TIM-
ING • Engine: Return to the original
trouble condition
• Timing light: Set
• Retard the ignition timing using CONSULT-III. If trouble symptom disappears, see
CHECK ITEM.
• Perform Idle Air Volume Learning.
POWER BAL-
ANCE • Engine: After warming up, idle the
engine.
• A/C switch: OFF
• Selector lever: P or N
• Cut off each injector signal one at a time using CONSULT-III. Engine runs rough or dies. • Harness and connectors
• Compression
• Fuel injector
• Power transistor
•Spark plug
• Ignition coil
COOLING FAN* • Ignition switch: ON
• Turn the cooling fan HI and OFF
using CONSULT-III. Cooling fan moves and stops.
• Harness and connectors
• Cooling fan motor
•IPDM E/R
ENG COOLANT
TEMP • Engine: Return to the original
trouble condition
• Change the engine coolant tem-
perature using CONSULT-III. If trouble symptom disappears, see
CHECK ITEM. • Harness and connectors
• Engine coolant temperature sen-
sor
• Fuel injector
FUEL PUMP RE-
LAY • Ignition switch: ON
(Engine stopped)
• Turn the fuel pump relay ON and
OFF using CONSULT-III and lis-
ten to operating sound. Fuel pump relay makes the operat-
ing sound.
• Harness and connectors
• Fuel pump relay
Revision: March 2010
2008 QX56

TROUBLE DIAGNOSIS - SPECIFICATION VALUEEC-75
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COMPONENT DIAGNOSIS
TROUBLE DIAGNOSIS - SPECIFICATION VALUE
DescriptionINFOID:0000000001351351
The specification (SP) value indicates the tolerance of
the value that is displayed in “SPEC” of “DATA MONI-
TOR” mode with CONSULT-III during normal operation of the Engine Control System. When the value in
“SPEC” of “DATA MONITOR” mode is within the SP value, the Engine Control Syst em is confirmed OK. When
the value in “SPEC” of “DATA MONITOR” mode is NOT within the SP value, the Engine Control System may
have one or more malfunctions.
The SP value is used to detect malfunctions that may af fect the Engine Control System, but will not light the
MIL.
The SP value will be displayed for the following three items:
• B/FUEL SCHDL (The fuel injection pulse width programmed into ECM prior to any learned on board correc- tion)
• A/F ALPHA-B1/B2 (The mean value of air-fuel ratio feedback correction factor per cycle)
• MAS A/F SE-B1 (The signal voltage of the mass air flow sensor)
Testing ConditionINFOID:0000000001351352
• Vehicle driven distance: More than 5,000 km (3,107 miles)
• Barometric pressure: 98.3 - 104.3 kPa (1.003 - 1.064 kg/cm
2 , 14.25 - 15.12 psi)
• Atmospheric temperature: 20 - 30 °C (68 - 86° F)
• Engine coolant temperature: 75 - 95 °C (167 - 203° F)
• Engine speed: Idle
• Transmission: Warmed-up
- After the engine is warmed up to normal operating temper ature, drive vehicle until “ATF TEMP SE 1” (A/T
fluid temperature sensor signal) indicates more than 60 °C (140° F).
• Electrical load: Not applied
- Rear window defogger switch, air conditioner switch, lighting switch are OFF. Steering wheel is straight
ahead.
Inspection ProcedureINFOID:0000000001351353
NOTE:
Perform “SPEC” in “DATA MONITOR” mode in maximum scale display.
1. Perform EC-13, "
Basic Inspection" .
2. Confirm that the testing conditions indicated above are met.
3. Select “B/FUEL SCHDL”, “A/F ALPHA-B1”, “A/F ALPHA-B2” and “MAS A/F SE-B1” in “SPEC” of “DATA
MONITOR” mode with CONSULT-III.
4. Make sure that monitor items are within the SP value.
5. If NG, go to EC-76, "
Diagnosis Procedure" .
Revision: March 2010 2008 QX56

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>> GO TO 8.
8.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that the each indication is within the SP value.
OK or NG
OK >> INSPECTION END
NG >> GO TO 9.
9.PERFORM POWER BALANCE TEST
1. Perform “POWER BALANCE ” in “ACTIVE TEST” mode.
2. Make sure that the each cylinder produces a momentary engine speed drop.
OK or NG
OK >> GO TO 12.
NG >> GO TO 10.
10.DETECT MALFUNCTIONING PART
1. Check the following.
- Ignition coil and its circuit (Refer to EC-411, "
Diagnosis Procedure" .)
- Fuel injector and its circuit (Refer to EC-399, "
Diagnosis Procedure" .)
- Intake air leakage
- Low compression pressure (Refer to EM-23, "
Checking Compression Pressure".)
2. If NG, repair or replace the malfunctioning part. If OK, replace fuel injector. (It may be caus ed by leakage from fuel injector or clogging.)
>> GO TO 11.
11 .CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that the each indication is within the SP value.
OK or NG
OK >> INSPECTION END
NG >> GO TO 12.
12.CHECK A/F SENSOR 1 FUNCTION
Perform all DTC Confirmation Procedure related with A/F sensor 1.
• For DTC P0130, P0150, refer to EC-141, "
DTC Confirmation Procedure" .
• For DTC P0131, P0151, refer to EC-145, "
DTC Confirmation Procedure" .
• For DTC P0132, P0132, refer to EC-149, "
DTC Confirmation Procedure" .
• For DTC P0133, P0153, refer to EC-153, "
DTC Confirmation Procedure" .
• For DTC P2A00, P2A03, refer to EC-385, "
DTC Confirmation Procedure" .
OK or NG
OK >> GO TO 15.
NG >> GO TO 13.
13.CHECK A/F SENSOR 1 CIRCUIT
Perform Diagnostic Procedure according to corresponding DTC.
>> GO TO 14.
14.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that the each indication is within the SP value.
OK or NG
Revision: March 2010 2008 QX56

EC-80
< COMPONENT DIAGNOSIS >[VK56DE]
TROUBLE DIAGNOSIS - SPECIFICATION VALUE
OK >>
INSPECTION END
NG >> GO TO 15.
15.DISCONNECT AND RECONNE CT ECM HARNESS CONNECTOR
1. Stop the engine.
2. Disconnect ECM harness connector. Check pin terminal and connector for damage, and then reconnect it.
>> GO TO 16.
16.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1”, “A/F AL PHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that the
each indication is within the SP value.
OK or NG
OK >> INSPECTION END
NG >> Detect malfunctioning part according to EC-481, "
Symptom Matrix Chart" .
17.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and make sure that the indication is within the
SP value.
OK or NG
OK >> INSPECTION END
NG (More than the SP value)>>GO TO 18.
NG (Less than the SP value)>>GO TO 25.
18.DETECT MALFUNCTIONING PART
1. Check for the cause of large engine friction. Refer to the following.
- Engine oil level is too high
- Engine oil viscosity
- Belt tension of power steering, alternat or, A/C compressor, etc. is excessive
- Noise from engine
- Noise from transmission, etc.
2. Check for the cause of insufficient combustion. Refer to the following.
- Valve clearance malfunction
- Intake valve timing control function malfunction
- Camshaft sprocket installation malfunction, etc.
>> Repair or replace malfunctioning part, and then GO TO 30.
19.CHECK INTAKE SYSTEM
Check for the cause of uneven air flow through mass air flow sensor. Refer to the following.
• Crushed air ducts
• Malfunctioning seal of air cleaner element
• Uneven dirt of air cleaner element
• Improper specification of intake air system
OK or NG
OK >> GO TO 21.
NG >> Repair or replace malfunctioning part, and then GO TO 20.
20.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”, AND “B/FUEL SCHDL”
Select “A/F ALPHA-B1”, “A/F ALPHA-B2”, and “B/F UEL SCHDL” in “SPEC” of “DATA MONITOR” mode, and
make sure that the each indication is within the SP value.
OK or NG
OK >> INSPECTION END
NG (“B/FUEL SCHDL” is more, “A/F ALPHA-B1”, “A/F ALPHA-B2” are less than the SP value)>>GO TO 21.
21.DISCONNECT AND RECONNECT MASS AIR FLOW SENSOR HARNESS CONNECTOR
1. Stop the engine.
Revision: March 2010 2008 QX56

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2. Disconnect mass air flow sensor harness connecto
r. Check pin terminal and connector for damage and
then reconnect it again.
>> GO TO 22.
22.CHECK “A/F ALPHA-B1”, “A/F ALPHA-B2”
1. Start engine.
2. Select “A/F ALPHA-B1”, “A/F ALPHA-B2” in “SPEC” of “DATA MONITOR” mode, and make sure that the each indication is within the SP value.
OK or NG
OK >> 1. Detect malfunctioning part of mass air flow sensor circuit and repair it. Refer to EC-113 .
2. GO TO 29.
NG >> GO TO 23.
23.CHECK “MAS A/F SE-B1”
Select “MAS A/F SE-B1” in “SPEC” of “DATA MONITOR” mode, and make sure that the indication is within the
SP value.
OK or NG
OK >> GO TO 24.
NG (More than the SP value)>>Replace ma ss air flow sensor, and then GO TO 29.
24.REPLACE ECM
1. Replace ECM.
2. Perform initialization of IVIS(NATS) system and registration of all IVIS(NATS) ignition key IDs. Refer to SEC-8, "
ECM RE-COMMUNICATING FUNCTION : Special Repair Requirement".
3. Perform EC-17, "
VIN Registration" .
4. Perform EC-18, "
Accelerator Pedal Released Position Learning" .
5. Perform EC-18, "
Throttle Valve Closed Position Learning" .
6. Perform EC-18, "
Idle Air Volume Learning" .
>> GO TO 29.
25.CHECK INTAKE SYSTEM
Check for the cause of uneven air flow through mass air flow sensor. Refer to the following.
• Crushed air ducts
• Malfunctioning seal of air cleaner element
• Uneven dirt of air cleaner element
• Improper specification of intake air system
OK or NG
OK >> GO TO 27.
NG >> Repair or replace malfunctioning part, and then GO TO 26.
26.CHECK “B/FUEL SCHDL”
Select “B/FUEL SCHDL” in “SPEC” of “DATA MONITOR” m ode, and make sure that the indication is within the
SP value.
OK or NG
OK >> INSPECTION END
NG (Less than the SP value)>>GO TO 27.
27.CHECK “MAS A/F SE-B1”
Select “MAS A/F SE-B1” in “SPEC” of “DATA MONITOR” mode, and make sure that the indication is within the
SP value.
OK or NG
OK >> GO TO 28.
NG (Less than the SP value)>>Replace ma ss air flow sensor, and then GO TO 30.
28.CHECK INTAKE SYSTEM
Check for the cause of air leak after the mass air flow sensor. Refer to the following.
Revision: March 2010 2008 QX56

P0031, P0032, P0051, P0052 A/F SENSOR 1 HEATER
EC-97
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P0031, P0032, P0051, P0052
A/F SENSOR 1 HEATER
DescriptionINFOID:0000000001351384
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:0000000001351378
DTC Confirmation ProcedureINFOID:0000000001351379
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confi rm that battery voltage is between 10.5V and 16V at
idle.
WITH CONSULT-III
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-97, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001351381
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 functionActuator
Camshaft position sensor (PHASE)
Crankshaft position sensor (POS) Engine speed
Air fuel ratio (A/F) sensor 1
heater controlAir fuel ratio (A/F) sensor 1
heater
Mass air flow sensor Amount of intake air
DTC No. Trouble diagnosis name DTC detecting conditionPossible 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: March 2010
2008 QX56