2004 INFINITI QX56 Factory Service Manual

Page 1665 of 3371

INFINITI QX56 2004  Factory Service Manual EC-474Revision: August 2007
DTC P1278, P1288 A/F SENSOR 1
2004 QX56
Intake air leaks
Exhaust gas leaks
Incorrect fuel pressure
Lack of fuel
Injectors
Incorrect PCV hose connection
PCV valve
Ma

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INFINITI QX56 2004  Factory Service Manual DTC P1278, P1288 A/F SENSOR 1
EC-475
C
D
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EC
Revision: August 20072004 QX56
Wiring DiagramUBS00HAJ
BANK 1
BBWA1369E

Page 1667 of 3371

INFINITI QX56 2004  Factory Service Manual EC-476Revision: August 2007
DTC P1278, P1288 A/F SENSOR 1
2004 QX56
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals

Page 1668 of 3371

INFINITI QX56 2004  Factory Service Manual DTC P1278, P1288 A/F SENSOR 1
EC-477
C
D
E
F
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MA
EC
Revision: August 20072004 QX56
BANK 2
BBWA0919E

Page 1669 of 3371

INFINITI QX56 2004  Factory Service Manual EC-478Revision: August 2007
DTC P1278, P1288 A/F SENSOR 1
2004 QX56
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals

Page 1670 of 3371

INFINITI QX56 2004  Factory Service Manual DTC P1278, P1288 A/F SENSOR 1
EC-479
C
D
E
F
G
H
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MA
EC
Revision: August 20072004 QX56
3. CHECK EXHAUST GAS LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before thr

Page 1671 of 3371

INFINITI QX56 2004  Factory Service Manual EC-480Revision: August 2007
DTC P1278, P1288 A/F SENSOR 1
2004 QX56
5. CLEAR THE SELF-LEARNING DATA
 With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select “SELF-L

Page 1672 of 3371

INFINITI QX56 2004  Factory Service Manual DTC P1278, P1288 A/F SENSOR 1
EC-481
C
D
E
F
G
H
I
J
K
L
MA
EC
Revision: August 20072004 QX56
6. CHECK A/F SENSOR 1 POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect A/F sensor 1 harness