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Nissan Pathfinder (2005 year). Manual - part 205

DTC P1271, P1281 A/F SENSOR 1

EC-491

2005 Pathfinder

Removal and Installation

UBS00KE8

AIR FUEL RATIO (A/F) SENSOR 1

Refer to

EM-21, "EXHAUST MANIFOLD AND THREE WAY CATALYST"

EC-492

DTC P1272, P1282 A/F SENSOR 1

2005 Pathfinder

DTC P1272, P1282 A/F SENSOR 1

PFP:22693

Component Description

UBS00KE9

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 Mode

UBS00KEA

Specification data are reference values.

On Board Diagnosis Logic

UBS00KEB

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 Procedure

UBS00KEC

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

Start engine and warm it up to normal operating temperature.

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)

DTC P1272, P1282 A/F SENSOR 1

EC-493

2005 Pathfinder

Check “A/F SEN1 (B1)” or “A/F SEN1 (B2)” indication.
If the indication is constantly approx. 5V, go to

EC-497, "Diag-

nostic Procedure"

If the indication is not constantly approx. 5V, go to next step.

Turn ignition switch OFF, wait at least 10 seconds and then
restart engine.

Drive and accelerate vehicle to more than 40 km/h (25 MPH)
within 20 seconds after restarting engine.

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.

If 1st trip DTC is displayed, go to

EC-497, "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

EC-494

DTC P1272, P1282 A/F SENSOR 1

2005 Pathfinder

Wiring Diagram

UBS00KED

BANK 1

BBWA1730E

DTC P1272, P1282 A/F SENSOR 1

EC-495

2005 Pathfinder

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)

A/F sensor 1 (Bank 1)

[Engine is running]

●

Warm-up condition

●

Idle speed

Approximately 3.1V

Approximately 2.6V

Approximately 2.3V

EC-496

DTC P1272, P1282 A/F SENSOR 1

2005 Pathfinder

BANK 2

BBWA1731E

DTC P1272, P1282 A/F SENSOR 1

EC-497

2005 Pathfinder

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 Procedure

UBS00KEE

CHECK GROUND CONNECTIONS

Turn ignition switch OFF.

Loosen and retighten three ground screws.Refer to

EC-165, "Ground Inspection"

OK or NG

>> GO TO 2.

>> Repair or replace ground connections.

TERMI-

NAL

NO.

WIRE

COLOR

ITEM

CONDITION

DATA (DC Voltage)

A/F sensor 1 (Bank 2)

[Engine is running]

●

Warm-up condition

●

Idle speed

Approximately 2.6V

Approximately 2.3V

Approximately 3.1V

Approximately 2.3V

BBIA0539E

EC-498

DTC P1272, P1282 A/F SENSOR 1

2005 Pathfinder

CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY CIRCUIT

Disconnect air fuel ratio (A/F) sensor 1 harness connector.

Turn ignition switch ON.

Check voltage between air fuel ratio (A/F) sensor 1 terminal 3
and ground with CONSULT-II or tester.

OK or NG

>> GO TO 4.

>> GO TO 3.

DETECT MALFUNCTIONING PART

Check the following.

●

Harness connectors E5, F14

●

IPDM E/R connector E119

●

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

BBIA0544E

PBIB1683E

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