2004 INFINITI QX56 fuel cap

DTC P1276, P1286 A/F SENSOR 1
EC-463
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Revision: August 20072004 QX56
DTC P1276, P1286 A/F SENSOR 1PFP:22693
Component DescriptionUBS00HA7
The air fuel ratio (A/F) sensor 1 is a planar dual-cell limit current sen-
sor. The sensor element of the A/F sensor 1 is the combination of a
Nernst concentration cell (sensor cell) with an oxygen-pump cell,
which transports ions. It has a heater in the element.
The sensor is capable of precise measurement = 1, but also in the
lean and rich range. Together with its control electronics, the sensor
outputs a clear, continuous signal throughout a wide range (0.7 <
< air).
The exhaust gas components diffuse through the diffusion gap at the
electrode of the oxygen pump and Nernst concentration cell, where
they are brought to thermodynamic balance.
An electronic circuit controls the pump current through the oxygen-
pump cell so that the composition of the exhaust gas in the diffusion
gap remains constant at = 1. Therefore, the A/F sensor 1 is able to
indicate air/fuel ratio by this pumping of current. In addition, a heater
is integrated in the sensor to ensure the required operating tempera-
ture of 700 - 800°C (1,292 - 1,472°F).
CONSULT-II Reference Value in Data Monitor ModeUBS00HA8
Specification data are reference values.
On Board Diagnosis LogicUBS00HA9
To judge the malfunction, the diagnosis checks that the A/F signal computed by ECM from the A/F sensor 1
signal fluctuates according to fuel feedback control.
DTC Confirmation ProcedureUBS00HAA
CAUTION:
Always drive vehicle at a safe speed.
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, confirm that battery voltage is more than 11V at idle.
WITH CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select “A/F SEN1 (B1)” or “A/F SEN1 (B2)” in “DATA MONITOR” mode with CONSULT-II.
3. Check “A/F SEN1 (B1)” or “A/F SEN1 (B2)” indication.
SEF 5 79 Z
SEF 5 80 Z
MONITOR ITEM CONDITION SPECIFICATION
A/F SEN1 (B1)
A/F SEN1 (B2)

Engine: After warming upMaintaining engine speed at
2,000 rpmFluctuates around 1.5V
DTC No. Trouble diagnosis name DTC detecting condition Possible Cause
P1276
1276
(Bank 1)
Air fuel ratio (A/F) sensor 1
circuit high voltage

The A/F signal computed by ECM from the A/F
sensor 1 signal is constantly approx. 1.5V.

Harness or connectors
(The A/F sensor 1 circuit is open or
shorted.)

Air fuel ratio (A/F) sensor 1
P1286
1286
(Bank 2)

EC-472Revision: August 2007
DTC P1278, P1288 A/F SENSOR 1
2004 QX56
DTC P1278, P1288 A/F SENSOR 1PFP:22693
Component DescriptionUBS00HAF
The air fuel ratio (A/F) sensor 1 is a planar dual-cell limit current sen-
sor. The sensor element of the A/F sensor 1 is the combination of a
Nernst concentration cell (sensor cell) with an oxygen-pump cell,
which transports ions. It has a heater in the element.
The sensor is capable of precise measurement = 1, but also in the
lean and rich range. Together with its control electronics, the sensor
outputs a clear, continuous signal throughout a wide range (0.7 <
< air).
The exhaust gas components diffuse through the diffusion gap at the
electrode of the oxygen pump and Nernst concentration cell, where
they are brought to thermodynamic balance.
An electronic circuit controls the pump current through the oxygen-
pump cell so that the composition of the exhaust gas in the diffusion
gap remains constant at = 1. Therefore, the A/F sensor 1 is able to
indicate air/fuel ratio by this pumping of current. In addition, a heater
is integrated in the sensor to ensure the required operating tempera-
ture of 700 - 800°C (1,292 - 1,472°F).
CONSULT-II Reference Value in Data Monitor ModeUBS00HAG
Specification data are reference values.
On Board Diagnosis LogicUBS00HAH
To judge the malfunction of A/F sensor 1, this diagnosis measures response time of the A/F signal computed
by ECM from the A/F sensor 1 signal. The time is compensated by engine operating (speed and load), fuel
feedback control constant, and the A/F sensor 1 temperature index. Judgment is based on whether the com-
pensated time (the A/F signal cycling time index) is inordinately long or not.
SEF 5 79 Z
SEF 5 80 Z
MONITOR ITEM CONDITION SPECIFICATION
A/F SEN1 (B1)
A/F SEN1 (B2)

Engine: After warming upMaintaining engine speed at
2,000 rpm Fluctuates around 1.5V
DTC No. Trouble diagnosis name DTC detecting condition Possible Cause
P1278
1278
(Bank 1)
Air fuel ratio (A/F) sensor 1
circuit slow response

The response (from RICH to LEAN) of the A/F
signal computed by ECM from A/F sensor 1
signal takes more than the specified time.

Harness or connectors
(The A/F sensor 1 circuit is open or
shorted.)

Air fuel ratio (A/F) sensor 1

Air fuel ratio (A/F) sensor 1 heater

Fuel pressure

Injector

Intake air leaks

Exhaust gas leaks

PCV

Mass air flow sensor P1288
1288
(Bank 2)

EC-484Revision: August 2007
DTC P1279, P1289 A/F SENSOR 1
2004 QX56
DTC P1279, P1289 A/F SENSOR 1PFP:22693
Component DescriptionUBS00HAM
The air fuel ratio (A/F) sensor 1 is a planar dual-cell limit current sen-
sor. The sensor element of the A/F sensor 1 is the combination of a
Nernst concentration cell (sensor cell) with an oxygen-pump cell,
which transports ions. It has a heater in the element.
The sensor is capable of precise measurement = 1, but also in the
lean and rich range. Together with its control electronics, the sensor
outputs a clear, continuous signal throughout a wide range (0.7 <
< air).
The exhaust gas components diffuse through the diffusion gap at the
electrode of the oxygen pump and Nernst concentration cell, where
they are brought to thermodynamic balance.
An electronic circuit controls the pump current through the oxygen-
pump cell so that the composition of the exhaust gas in the diffusion
gap remains constant at = 1. Therefore, the A/F sensor 1 is able to
indicate air/fuel ratio by this pumping of current. In addition, a heater
is integrated in the sensor to ensure the required operating tempera-
ture of 700 - 800°C (1,292 - 1,472°F).
CONSULT-II Reference Value in Data Monitor ModeUBS00HAN
Specification data are reference values.
On Board Diagnosis LogicUBS00HAO
To judge the malfunction of A/F sensor 1, this diagnosis measures response time of the A/F signal computed
by ECM from the air fuel ration A/F sensor 1 signal. The time is compensated by engine operating (speed and
load), fuel feedback control constant, and the A/F sensor 1 temperature index. Judgment is based on whether
the compensated time (the A/F signal cycling time index) is inordinately long or not.
SEF 5 79 Z
SEF 5 80 Z
MONITOR ITEM CONDITION SPECIFICATION
A/F SEN1 (B1)
A/F SEN1 (B2)

Engine: After warming upMaintaining engine speed at
2,000 rpmFluctuates around 1.5V
DTC No. Trouble diagnosis name DTC detecting condition Possible Cause
P1279
1279
(Bank 1)
Air fuel ratio (A/F) sensor 1
circuit slow response

The response (from LEAN to RICH) of the A/F
signal computed by ECM from A/F sensor 1
signal takes more than the specified time.

Harness or connectors
(The A/F sensor 1 circuit is open or
shorted.)

Air fuel ratio (A/F) sensor 1

Air fuel ratio (A/F) sensor 1 heater

Fuel pressure

Injector

Intake air leaks

Exhaust gas leaks

PCV

Mass air flow sensor P1289
1289
(Bank 2)

EC-636Revision: August 2007
EVAPORATIVE EMISSION SYSTEM
2004 QX56
Component InspectionUBS00HDZ
EVAP CANISTER
Check EVAP canister as follows:
1. Block port B .
2. Blow air into port A and check that it flows freely out of port C .
3. Release blocked port B .
4. Apply vacuum pressure to port B and check that vacuum pres-
sure exists at the ports A and C .
5. Block port A and B .
6. Apply pressure to port C and check that there is no leakage.
FUEL TANK VACUUM RELIEF VALVE (BUILT INTO FUEL FULLER CAP)
1. Wipe clean valve housing.
2. Check valve opening pressure and vacuum.
3. If out of specification, replace fuel filler cap as an assembly.
CAUTION:
Use only a genuine fuel filler cap as a replacement. If an incor-
rect fuel filler cap is used, the MIL may come on.
EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
Refer to EC-285 .
FUEL TANK TEMPERATURE SENSOR
Refer to EC-225 .
EVAP CANISTER VENT CONTROL VALVE
Refer to EC-292 .
EVAP CONTROL SYSTEM PRESSURE SENSOR
Refer to EC-299 .
BBIA0352E
SEF 4 45 Y
Pressure:
15.3 - 20.0 kPa (0.156 - 0.204 kg/cm2 , 2.22
- 2.90 psi)
Vac uu m :
−6.0 to −3.3 kPa (−0.061 to −0.034 kg/cm
2
, −0.87 to −0.48 psi)
SEF 9 43 S

PRECAUTIONS
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Revision: August 20072004 QX56
PRECAUTIONSPFP:00001
Precautions for Drain Engine CoolantEBS00IKY
Drain engine coolant when engine is cooled.
Precautions for Disconnecting Fuel PipingEBS00IKZ

Before starting work, make sure no fire or spark producing items are in the work area.

Release fuel pressure before disconnecting and disassembly.

After disconnecting pipes, plug openings to stop fuel leakage.
Precautions for Removal and DisassemblyEBS00IL0

When instructed to use special service tools, use the specified tools. Always be careful to work safely,
avoid forceful or uninstructed operations.

Exercise maximum care to avoid damage to mating or sliding surfaces.

Cover openings of engine system with tape or the equivalent, if necessary, to seal out foreign materials.

Mark and arrange disassembly parts in an organized way for easy troubleshooting and assembly.

When loosening nuts and bolts, as a basic rule, start with the one furthest outside, then the one diagonally
opposite, and so on. If the order of loosening is specified, do exactly as specified. Power tools may be
used where noted in the step.
Precautions for Inspection, Repair and ReplacementEBS00IL1
Before repairing or replacing, thoroughly inspect parts. Inspect new replacement parts in the same way, and
replace if necessary.
Precautions for Assembly and InstallationEBS00IL2

Use torque wrench to tighten bolts or nuts to specification.

When tightening nuts and bolts, as a basic rule, equally tighten in several different steps starting with the
ones in center, then ones on inside and outside diagonally in this order. If the order of tightening is speci-
fied, do exactly as specified.

Replace with new gasket, packing, oil seal or O-ring.

Thoroughly wash, clean, and air-blow each part. Carefully check engine oil or engine coolant passages for
any restriction and blockage.

Avoid damaging sliding or mating surfaces. Completely remove foreign materials such as cloth lint or dust.
Before assembly, oil sliding surfaces well.

Release air within route when refilling after draining engine coolant.

Before starting engine, apply fuel pressure to fuel lines with turning ignition switch ON (with engine
stopped). Then make sure that there are no leaks at fuel line connections.

After repairing, start engine and increase engine speed to check engine coolant, fuel, oil, and exhaust
systems for leakage.
Parts Requiring Angular TighteningEBS00IL3

For final tightening of the following engine parts use Tool:
–Cylinder head bolts
–Main bearing cap bolts
–Connecting rod cap bolts
–Crankshaft pulley bolt (No angle wrench is required as the bolt flange is provided with notches for angle
tightening)

Do not use a torque value for final tightening.

The torque value for these parts are for a preliminary step.

Ensure thread and seat surfaces are clean and lightly coated with engine oil. Tool number : KV10112100 (BT-8653-A)

PREPARATION
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Revision: August 20072004 QX56
PREPARATIONPFP:00002
Special Service ToolsEBS00IL5
The actual shapes of Kent-Moore tools may differ from those of special service tools illustrated here.
Tool number
(Kent-Moore No.)
Tool nameDescription
KV10111100
(J-37228)
Seal cutterRemoving steel oil pan and rear timing chain
case
KV991J0050
(J-44626)
Air fuel sensor SocketLoosening or tightening air fuel ratio A/F sen-
sor
a: 22 mm (0.87 in)
EG15050500
(J-45402)
Compression gauge adapterInspecting compression pressure
KV10116200
(J-26336-A)
Valve spring compressor
1. KV10115900
(J-26336-20)
Attachment
2. KV10109220
(—)
AdapterDisassembling valve mechanism
Part (1) is a component of KV10116200
(J26336-A), but part (2) is not.
KV10112100
(BT-8653-A)
Angle wrenchTightening bolts for bearing cap and cylinder
head
KV10107902
(J-38959)
Valve oil seal pullerRemoving valve oil seal
S-NT046
LBIA0444E
ZZA1225D
PBIC1650E
S-NT014
S-NT011

EM-16Revision: August 2007
INTAKE MANIFOLD
2004 QX56

Perform the following steps to disconnect the quick connector
using Tool.
a. Remove quick connector cap (engine side only).
b. With the sleeve side of Tool facing quick connector, install Tool
onto fuel tube.
c. Insert Tool into quick connector until sleeve contacts and goes
no further. Hold the Tool in that position.
CAUTION:
Inserting the Tool hard will not disconnect quick connector.
Hold Tool where it contacts and goes no further.
d. Draw and pull out quick connector straight from fuel tube.
CAUTION:

Pull quick connector holding A position in illustration.

Do not pull with lateral force applied. O-ring inside quick connector may be damaged.

Prepare container and cloth beforehand as fuel will leak out.

Avoid fire and sparks.

Be sure to cover openings of disconnected pipes with plug or plastic bag to avoid fuel leakage
and entry of foreign materials.
6. Remove or disconnect harnesses, brackets, vacuum hose, vacuum gallery and PCV hose and tube from
intake manifold.
7. Remove electric throttle control actuator by loosening bolts diagonally.
CAUTION:

Handle carefully to avoid any damage to the electric throttle control actuator.

Do not disassemble.
8. Remove the fuel injectors and fuel tube assembly. Refer to EM-29, "
Removal and Installation" .
9. Loosen the bolts in reverse order shown using power tool.
10. Remove the intake manifold.
CAUTION:
Cover engine openings to avoid entry of foreign materials.Tool number : 16441 6N210 (J-45488)
SBIA0354E
WBIA0604E
KBIA2462E

INTAKE MANIFOLD
EM-17
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Revision: August 20072004 QX56
INSTALLATION
Installation is in the reverse order of removal.

Tighten the intake manifold bolts in numerical order as shown.

Install the EVAP canister purge control solenoid valve connector with it facing front of engine.

Tighten the electronic throttle control actuator bolts of the electric throttle control actuator equally and
diagonally in several steps.

After installation perform procedure in EM-18, "INSPECTION AFTER INSTALLATION" .

Install the water hose so that its overlap width for connection is between 27 mm (1.06 in) and 32 mm (1.26
in) (target: 27 mm 1.06 in).
Connecting Quick Connector of Fuel Tube
Install quick connector as follows (the steps are the same for quick connectors on both engine side and vehi-
cle side except for the quick connector cap).
1. Make sure no foreign substances are deposited in and around tube and quick connector, and they are not
damaged.
2. Thinly apply new engine oil around the fuel tube from tip end to the spool end.
3. Align center to insert quick connector straight into fuel tube.

Insert until the paint mark for engagement identification
(white) goes completely inside quick connector so that you
cannot see it from the straight side of the connected part. Use
a mirror to check this where it is not possible to view directly
from the straight side, such as quick connector on vehicle
side.

Insert fuel tube into quick connector until top spool is com-
pletely inside quick connector, and 2nd level spool exposes
right below quick connector on engine side.
CAUTION:

Hold A position in illustration when inserting fuel tube
into quick connector.

Carefully align center to avoid inclined insertion to pre-
vent damage to O-ring inside quick connector.

Insert until you hear a “click” sound and actually feel
the engagement.

To avoid misidentification of engagement with a similar
sound, be sure to perform the next step.
4. Pull quick connector by hand holding A position. Make sure it is completely engaged (connected) so that it
does not come out from fuel tube.
NOTE:
Recommended pulling force is 50 N (5.1 kg, 11.2 lb).
KBIA2462E
PBIC0017E
KBIA0272E