2005 INFINITI QX4 Factory Service Manual

tailgate carplay catalytic converter clock reset inflation pressure coolant reservoir

Page 1697 of 3419

INFINITI QX4 2005 Factory Service Manual EC-506Revision: October 2005
DTC P1276, P1286 A/F SENSOR 1
2005 QX56
Removal and InstallationUBS00HAE
AIR FUEL RATIO (A/F) SENSOR 1
Refer to EM-19, "EXHAUST MANIFOLD AND THREE WAY CATALYST" .

Page 1698 of 3419

INFINITI QX4 2005 Factory Service Manual DTC P1278, P1288 A/F SENSOR 1
EC-507
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Revision: October 20052005 QX56
DTC P1278, P1288 A/F SENSOR 1PFP:22693
Component DescriptionUBS00HAF
The air fuel ratio (A/F) sensor 1 is

DTC P1278, P1288 A/F SENSOR 1
EC-507
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Revision: October 20052005 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
Fuel injector
Intake air leaks
Exhaust gas leaks
PCV
Mass air flow sensor P1288
1288
(Bank 2)

Page 1699 of 3419

INFINITI QX4 2005 Factory Service Manual EC-508Revision: October 2005
DTC P1278, P1288 A/F SENSOR 1
2005 QX56
DTC Confirmation ProcedureUBS00HAI
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch O

EC-508Revision: October 2005
DTC P1278, P1288 A/F SENSOR 1
2005 QX56
DTC Confirmation ProcedureUBS00HAI
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. 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 1minute under no load.
4. Let engine idle for 1 minute.
5. Select “A/F SEN1(B1) P1278/P1279” or “A/F SEN1(B1) P1288/P1289” of “A/F SEN1” in “DTC WORK
SUPPORT” mode with CONSULT-II.
6. Touch “START”.
If “COMPLETED” appears on CONSULT-II screen, go to step
10.
If “COMPLETED” does not appear on CONSULT-II screen, go to
the following step.
7. After perform the following procedure, “TESTING” will be dis-
played on the CONSULT-II screen.
a. Increase the engine speed up to 4,000 to 5,000 rpm and keep it
for 10 seconds.
b. Fully release accelerator pedal and then let engine idle for about
10 seconds.
If “TESTING” is not displayed after 10 seconds, refer to EC-
146, "TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
8. Wait for about 20 seconds at idle at under the condition that
“TESTING” is displayed on the CONSULT-II screen.
9. Make sure that “TESTING” changes to “COMPLETED”.
If “TESTING” changed to “OUT OF CONDITION”, refer to
EC-146, "
TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
10. Make sure that “OK” is displayed after touching “SELF-DIAG
RESULT”.
If “NG” is displayed, go to EC-513, "
Diagnostic Procedure" .
WITH GST
1. Start engine and warm it up to normal operating temperature.
2. Select Service $01 with GST.
3. Calculate the total value of “Short term fuel trim” and “Long term fuel trim” indications.
Make sure that the total percentage should be within ±15%.
If OK, go to the following step.
If NG, check the following.
PBIB0756E
PBIB1925E
PBIB0758E

Page 1700 of 3419

INFINITI QX4 2005 Factory Service Manual DTC P1278, P1288 A/F SENSOR 1
EC-509
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Revision: October 20052005 QX56
Intake air leaks
Exhaust gas leaks
Incorrect fuel pressure
Lack of fuel
Fuel injector
Incorrect PCV

Page 1701 of 3419

INFINITI QX4 2005 Factory Service Manual EC-510Revision: October 2005
DTC P1278, P1288 A/F SENSOR 1
2005 QX56
Wiring DiagramUBS00HAJ
BANK 1
BBWA1700E

Page 1702 of 3419

INFINITI QX4 2005 Factory Service Manual DTC P1278, P1288 A/F SENSOR 1
EC-511
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Revision: October 20052005 QX56
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do no

Page 1703 of 3419

INFINITI QX4 2005 Factory Service Manual EC-512Revision: October 2005
DTC P1278, P1288 A/F SENSOR 1
2005 QX56
BANK 2
BBWA1701E

Page 1704 of 3419

INFINITI QX4 2005 Factory Service Manual DTC P1278, P1288 A/F SENSOR 1
EC-513
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Revision: October 20052005 QX56
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do no

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