Nissan Pathfinder (2008 year). Manual - part 341

P2138 APP SENSOR

EC-845

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P2138 APP SENSOR

Component Description

INFOID:0000000001537979

The accelerator pedal position sensor is installed on the upper end
of the accelerator pedal assembly. The sensor detects the accelera-
tor position and sends a signal to the ECM.
Accelerator pedal position sensor has two sensors. These sensors
are a kind of potentiometers which transform the accelerator pedal
position into output voltage, and emit the voltage signal to the ECM.
In addition, these sensors detect the opening and closing speed of
the accelerator pedal and feed the voltage signals to the ECM. The
ECM judges the current opening angle of the accelerator pedal from
these signals and controls the throttle control motor based on these
signals.
Idle position of the accelerator pedal is determined by the ECM
receiving the signal from the accelerator pedal position sensor. The ECM uses this signal for the engine oper-
ation such as fuel cut. 

On Board Diagnosis Logic

INFOID:0000000001537980

This self-diagnosis has the one trip detection logic.
NOTE:
If DTC P2138 is displayed with DTC P0643, first perform the trouble diagnosis for DTC P0643. Refer to

EC-770

.

FAIL-SAFE MODE

When the malfunction is detected, ECM enters fail-safe mode and the MIL lights up.

DTC Confirmation Procedure

INFOID:0000000001537981

NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next step.
1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 8V at idle.
1.

Start engine and let it idle for 1 second.

2.

Check DTC.

3.

If DTC is detected, go to 

EC-846, "Diagnosis Procedure"

.

PBIB1741E

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P2138
2138

Accelerator pedal position 
sensor circuit range/per-
formance

Rationally incorrect voltage is sent to ECM 
compared with the signals from APP sensor 1 
and APP sensor 2.

• Harness or connector

(APP sensor 1 and 2 circuit is open or 
shorted.)
(TP sensor circuit is shorted.)

• Accelerator pedal position sensor 1 and 2
• Electric throttle control actuator

(TP sensor)

Engine operating condition in fail-safe mode

The ECM controls the electric throttle control actuator in regulating the throttle opening in order for the idle position to be within +10 
degrees.
The ECM regulates the opening speed of the throttle valve to be slower than the normal condition.
So, the acceleration will be poor. 

EC-846

< COMPONENT DIAGNOSIS >

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P2138 APP SENSOR

Diagnosis Procedure

INFOID:0000000001537982

1.

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten three ground screws on the body.
Refer to 

EC-565, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

CHECK APP SENSOR 1 POWER SUPPLY CIRCUIT

1.

Disconnect accelerator pedal position (APP) sensor (1) harness
connector.

2.

Turn ignition switch ON.

3.

Check voltage between APP sensor terminal 2 and ground with
CONSULT-III or tester.

OK or NG

OK

>> GO TO 3.

NG

>> Repair open circuit or short to ground or short to power

in harness or connectors.

3.

CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-I

1.

Turn ignition switch ON.

2.

Check voltage between APP sensor terminal 1 and ground with
CONSULT-III or tester.

OK or NG

OK

>> GO TO 8.

NG

>> GO TO 4.

BBIA0539E

AWBIA0079ZZ

Voltage: Approximately 5V

PBIB2608E

Voltage: Approximately 5V

PBIB2611E

P2138 APP SENSOR

EC-847

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4.

CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-II

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check harness continuity between APP sensor terminal 1 and ECM terminal 91.
Refer to Wiring Diagram.

OK or NG

OK

>> GO TO 5.

NG

>> Repair open circuit in harness or connectors.

5.

CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-III

Check harness for short to power and short to ground, between the following terminals

OK or NG

OK

>> GO TO 6.

NG

>> Repair short to ground or short to power in harness connectors.

6.

CHECK THROTTLE POSITION SENSOR

Refer to 

EC-848, "Component Inspection"

.

OK or NG

OK

>> GO TO 12.

NG

>> GO TO 7.

7.

REPLACE ELECTRIC THROTTLE CONTROL ACTUATOR

1.

Replace the electric throttle control actuator.

2.

Perform 

EC-497, "Throttle Valve Closed Position Learning"

.

3.

Perform 

EC-497, "Idle Air Volume Learning"

.

>> INSPECTION END

8.

CHECK APP SENSOR GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check harness continuity between ECM terminal 82 and APP sensor terminal 4, ECM terminal 83 and
APP sensor terminal 5.
Refer to Wiring Diagram.

4.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 9.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

9.

CHECK APP SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Check harness continuity between ECM terminal 106 and APP sensor terminal 3, ECM terminal 98 and
APP sensor terminal 6.
Refer to Wiring Diagram.

2.

Also check harness for short to ground and short to power.

Continuity should exist.

ECM terminal

Sensor terminal

Reference Wiring Diagram

47

Electric throttle control actuator terminal 2

EC-897, "Wiring Diagram - ENGINE CONTROL SYSTEM 

-"

91

APP sensor terminal 1

Continuity should exist.

Continuity should exist.

EC-848

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[VK56DE]

P2138 APP SENSOR

OK or NG

OK

>> GO TO 10.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

10.

CHECK ACCELERATOR PEDAL POSITION SENSOR

Refer to 

EC-848, "Component Inspection"

.

OK or NG

OK

>> GO TO 12.

NG

>> GO TO 11.

11.

REPLACE ACCELERATOR PEDAL ASSEMBLY

1.

Replace the accelerator pedal assembly.

2.

Perform 

EC-497, "Accelerator Pedal Released Position Learning"

.

3.

Perform 

EC-497, "Throttle Valve Closed Position Learning"

.

4.

Perform 

EC-497, "Idle Air Volume Learning"

.

>> INSPECTION END

12.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-51, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000001537983

ACCELERATOR PEDAL POSITION SENSOR

1.

Reconnect all harness connectors disconnected.

2.

Turn ignition switch ON.

3.

Check voltage between ECM terminals 106 (APP sensor 1 sig-
nal), 98 (APP sensor 2 signal) and ground under the following
conditions.

4.

If NG, replace accelerator pedal assembly and go to next step.

5.

Perform 

EC-497, "Accelerator Pedal Released Position Learning"

.

6.

Perform 

EC-497, "Throttle Valve Closed Position Learning"

.

7.

Perform 

EC-497, "Idle Air Volume Learning"

.

Terminal

Accelerator pedal

Voltage

106
 (Accelerator pedal position 
sensor 1)

Fully released

0.65 - 0.87V

Fully depressed

More than 4.3V

98
(Accelerator pedal position 
sensor 2)

Fully released

0.28 - 0.48V

Fully depressed

More than 2.0V

MBIB0023E

P2A00, P2A03 A/F SENSOR 1

EC-849

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P2A00, P2A03 A/F SENSOR 1

Component Description

INFOID:0000000001537984

The air fuel ratio (A/F) sensor 1 is a planar one-cell limit current sen-
sor. The sensor element of the A/F sensor 1 is composed an elec-
trode layer, 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.
The exhaust gas components diffuse through the diffusion layer at
the sensor cell. An electrode layer is applied voltage, and this current
relative oxygen density in lean. Also this current relative hydrocar-
bon density in rich.
Therefore, the A/F sensor 1 is able to indicate air fuel ratio by this
electrode layer of current. In addition, a heater is integrated in the
sensor to ensure the required operating temperature of about 800

°

C

(1,472

°

F).

On Board Diagnosis Logic

INFOID:0000000001537985

To judge the malfunction, the A/F signal computed by ECM from the A/F sensor 1 signal is monitored not to be
shifted to LEAN side or RICH side.

DTC Confirmation Procedure

INFOID:0000000001537986

NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next step.
1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11V at idle.

 WITH CONSULT-III

1.

Start engine and warm it up to normal operating temperature.

2.

Turn ignition switch OFF and wait at least 10 seconds.

3.

Turn ignition switch ON.

4.

Turn ignition switch OFF and wait at least 10 seconds.

5.

Turn ignition switch ON and select “SELF-LEARNING CONT” in “WORK SUPPORT” mode with CON-
SULT-III.

PBIB3353E

PBIB3354E

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible Cause

P2A00
2A00
(Bank 1)

Air fuel ratio (A/F) sensor 1 
circuit range/performance

• The output voltage computed by ECM from the 

A/F sensor 1 signal is shifted to the lean side for 
a specified period.

• The A/F signal computed by ECM from the A/F 

sensor 1 signal is shifted to the rich side for a 
specified period.

• A/F sensor 1
• A/F sensor 1 heater
• Fuel pressure
• Fuel injector
• Intake air leaks

P2A03
2A03
(Bank 2)

EC-850

< COMPONENT DIAGNOSIS >

[VK56DE]

P2A00, P2A03 A/F SENSOR 1

6.

Clear the self-learning coefficient by touching “CLEAR”.

7.

Turn ignition switch OFF and wait at least 10 seconds.

8.

Turn ignition switch ON.

9.

Turn ignition switch OFF and wait at least 10 seconds.

10. Start engine and keep the engine speed between 3,500 and 4,000 rpm for 1 minute under no load.
11. Let engine idle for 1 minute.

12. Keep engine speed between 2,500 and 3,000 rpm for 20 minutes.

13. Check 1st trip DTC.

14. If 1st trip DTC is detected, go to 

EC-850, "Diagnosis Procedure"

.

 WITH GST

1.

Start engine and warm it up to normal operating temperature.

2.

Turn ignition switch OFF and wait at least 10 seconds.

3.

Turn ignition switch ON.

4.

Turn ignition switch OFF and wait at least 10 seconds.

5.

Disconnect mass air flow sensor (1) harness connector.

6.

Start engine and let it idle for at least 5 seconds.

7.

Stop engine and reconnect mass air flow sensor harness con-
nector.

8.

Select Service $03 with GST and make sure that DTC P0102 is
detected.

9.

Select Service $04 with GST and erase the DTC P0102.

10. Start engine and keep the engine speed between 3,500 and

4,000 rpm for 1 minute under no load.

11. Let engine idle for 1 minute.
12. Keep engine speed between 2,500 and 3,000 rpm for 20 minutes.

13. Select Service $07 with GST.

If 1st trip DTC is detected, go to 

EC-850, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000001537987

1.

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten two ground screws on the body.
Refer to 

EC-565, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

RETIGHTEN A/F SENSOR 1

Loosen and retighten the A/F sensor 1.
Refer to 

EM-170, "Removal and Installation"

.

Vehicle front

ALBIA0353ZZ

BBIA0539E

P2A00, P2A03 A/F SENSOR 1

EC-851

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>> GO TO 3.

3.

CHECK FOR INTAKE AIR LEAK

1.

Start engine and run it at idle.

2.

Listen for an intake air leak after the mass air flow sensor.

OK or NG

OK

>> GO TO 4.

NG

>> Repair or replace.

4.

CLEAR THE SELF-LEARNING DATA

 With CONSULT-III

1.

Start engine and warm it up to normal operating temperature.

2.

Select “SELF-LEARNING CONT” in “WORK SUPPORT” mode with CONSULT-III.

3.

Clear the self-learning control coefficient by touching “CLEAR”.

4.

Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected?
Is it difficult to start engine?

 Without CONSULT-III

1.

Start engine and warm it up to normal operating temperature.

2.

Turn ignition switch OFF.

3.

Disconnect mass air flow sensor (1) harness connector.

4.

Restart engine and let it idle for at least 5 seconds.

5.

Stop engine and reconnect mass air flow sensor harness con-
nector.

6.

Make sure DTC P0102 is displayed.

7.

Erase the DTC memory. Refer to 

EC-534, "Malfunction Indicator

Lamp (MIL)"

.

8.

Make sure DTC P0000 is displayed.

9.

Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected?
Is it difficult to start engine?

Yes or No

Yes

>> Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to 

EC-651

 or 

EC-656

.

No

>> GO TO 5.

5.

CHECK HARNESS CONNECTOR

1.

Turn ignition switch OFF.

2.

Disconnect A/F sensor 1 harness connector.

Vehicle front

ALBIA0353ZZ

ALBIA0360ZZ

1.

A/F sensor 1 (bank 2) harness connector

2.

A/F sensor 1 (bank 2)

3.

A/F sensor 1 (bank 1)

4.

A/F sensor 1 (bank 1) harness connector

: Vehicle front

EC-852

< COMPONENT DIAGNOSIS >

[VK56DE]

P2A00, P2A03 A/F SENSOR 1

3.

Check harness connector for water. 

OK or NG

OK

>> GO TO 6.

NG

>> Repair or replace harness connector.

6.

CHECK A/F SENSOR 1 POWER SUPPLY CIRCUIT

1.

Turn ignition switch ON.

2.

Check voltage between A/F sensor 1 terminal 4 and ground with
CONSULT-III or tester.

OK or NG

OK

>> GO TO 8.

NG

>> GO TO 7.

7.

DETECT MALFUNCTIONING PART

Check the following.
• Harness connectors E5, F14
• IPDM E/R harness connector E119
• 15A fuse
• Harness for open or short between A/F sensor 1 and fuse

>> Repair or replace harness or connectors.

8.

CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check harness continuity between A/F sensor 1 terminal and ECM terminal as follows.
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 power.

OK or NG

Water should not exit.

Voltage: Battery voltage

PBIB3308E

A/F sensor 1 terminal

ECM terminal

Bank1

1

35

2

56

Bank 2

1

16

2

75

Continuity should exist.

Bank 1

Bank 2

A/F sensor 1 terminal

ECM terminal

A/F sensor 1 terminal

ECM terminal

1

35

1

16

2

56

2

75

Continuity should not exist.