2005 INFINITI FX35 vq35de

DTC P1271, P1281 A/F SENSOR 1 EC-493
[VQ35DE]
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Revision: 2005 July 2005 FX
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
Diagnostic ProcedureABS00A9Y
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten ground three screws on the body. Refer to EC-170, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
TERMI-
NAL NO. WIRE
COLOR ITEM CONDITION DATA (DC Voltage)
57 G A/F sensor 1 (Bank 2) [Engine is running]

Warm-up condition

Idle speed Approximately 2.6V
58 Y Approximately 2.3V
76 P Approximately 3.1V
77 BR Approximately 2.3V
PBIB2625E

EC-494
[VQ35DE]
DTC P1271, P1281 A/F SENSOR 1
Revision: 2005 July 2005 FX
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 air fuel ratio (A/F) sensor 1 terminal 3 and ground with CONSULT-II or tester.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors E18, F48

Fuse block (J/B) connector E201

10A fuse

Harness for open or short between air fuel ratio (A/F) sensor 1 and fuse
>> Repair or replace harness or connectors.
Voltage: Battery voltage
PBIB2190E
PBIB1683E

DTC P1271, P1281 A/F SENSOR 1 EC-495
[VQ35DE]
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Revision: 2005 July 2005 FX
4. CHECK AIR FUEL RATIO (A/F) SENSOR 1 INPUT SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between the following terminals. Refer to Wiring Diagram.
4. Check harness continuity between the following terminals and ground. Refer to Wiring Diagram.
5. 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 INTERMITTENT INCIDENT
Perform EC-163, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
OK or NG
OK >> GO TO 6.
NG >> Repair or replace.
6. REPLACE AIR FUEL RATIO (A/F) SENSOR 1
Replace air fuel ratio (A/F) sensor 1.
CAUTION:

Discard any air fuel ratio (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 air fuel ratio (A/F) sensor, clean exhaust system threads using Heated Oxy-
gen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
>> INSPECTION END
A/F sensor 1 terminal ECM terminal
Bank1 116
275
535
656
Bank 2 176
277
557
658
Continuity should exist.
Bank 1 Bank 2
A/F sensor 1 terminal ECM terminal A/F sensor 1 terminal ECM terminal 116176
275277
535557
656658
Continuity should not exist.

EC-496
[VQ35DE]
DTC P1271, P1281 A/F SENSOR 1
Revision: 2005 July 2005 FX
Removal and InstallationABS00A9Z
AIR FUEL RATIO (A/F) SENSOR 1
Refer to EM-26, "EXHAUST MANIFOLD AND THREE WAY CATALYST" .

DTC P1272, P1282 A/F SENSOR 1 EC-497
[VQ35DE]
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Revision: 2005 July 2005 FX
DTC P1272, P1282 A/F SENSOR 1PFP:22693
Component DescriptionABS00AA0
The air fuel ratio (A/F) sensor is a planar dual-cell limit current sen-
sor. The sensor element of the air fuel ratio (A/F) sensor is the com-
bination 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 air fuel ratio (A/F) sen-
sor 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 temperature of 700 - 800 °C (1,292 - 1,472 °F).
CONSULT-II Reference Value in Data Monitor ModeABS00AA1
Specification data are reference values.
On Board Diagnosis LogicABS00AA2
To judge the malfunction, the diagnosis checks that the A/F signal computed by ECM from the air fuel ratio (A/
F) sensor 1 signal is not inordinately high.
DTC Confirmation ProcedureABS00AA3
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.
SEF579Z
SEF580Z
MONITOR ITEM CONDITION SPECIFICATION
A/F SEN1 (B1)
A/F SEN1 (B2)

Engine: After warming up Maintaining engine speed at
2,000 rpm Fluctuates around 1.5V
DTC No. Trouble diagnosis name DTC detecting condition Possible Cause
P1272
1272
(Bank 1) Air fuel ratio (A/F) sensor 1
circuit no activity detected

The A/F signal computed by ECM from the air
fuel ratio (A/F) sensor 1 signal is constantly
approx. 5V.
Harness or connectors
(The air fuel ratio (A/F) sensor 1 cir-
cuit is open or shorted.)

Air fuel ratio (A/F) sensor 1
P1282
1282
(Bank 2)

EC-498
[VQ35DE]
DTC P1272, P1282 A/F SENSOR 1
Revision: 2005 July 2005 FX
3. Check “A/F SEN1 (B1)” or “A/F SEN1 (B2)” indication.
If the indication is constantly approx. 5V, go to EC-502, "
Diag-
nostic Procedure" .
If the indication is not constantly approx. 5V, go to next step.
4. Turn ignition switch OFF, wait at least 10 seconds and then restart engine.
5. Drive and accelerate vehicle to more than 40 km/h (25 MPH) within 20 seconds after restarting engine.
6. Maintain the following conditions for about 20 consecutive sec- onds.
NOTE:

Keep the accelerator pedal as steady as possible during the cruising.

If this procedure is not completed within 1 minute after restarting engine at step 4, return to step
4.
7. If 1st trip DTC is displayed, go to EC-502, "
Diagnostic Procedure" .
WITH GST
Follow the procedure “WITH CONSULT-II” above.
ENG SPEED 1,000 - 3,200 rpm
VHCL SPEED SE More than 40 km/h (25 MPH)
B/FUEL SCHDL 1.5 - 9.0 msec
Gear position Suitable position
SEF581Z

DTC P1272, P1282 A/F SENSOR 1 EC-499
[VQ35DE]
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Revision: 2005 July 2005 FX
Wiring DiagramABS00AA4
BANK 1
TBWM0390E

EC-500
[VQ35DE]
DTC P1272, P1282 A/F SENSOR 1
Revision: 2005 July 2005 FX
Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL NO. WIRE
COLOR ITEM CONDITION DATA (DC Voltage)
16 G A/F sensor 1 (Bank 1) [Engine is running]

Warm-up condition

Idle speed Approximately 3.1V
35 B/R Approximately 2.6V
56 L Approximately 2.3V
75 R/B Approximately 2.3V