Infiniti FX35 / FX45. Manual - part 422

DTC P1226 TP SENSOR

EC-449

< SERVICE INFORMATION >

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DTC P1226 TP SENSOR

Component Description

INFOID:0000000001326304

Electric throttle control actuator consists of throttle control motor,
throttle position (TP) sensor, etc. The throttle position sensor
responds to the throttle valve movement. 
The throttle position sensor has two sensors. These sensors are a
kind of potentiometers which transform the throttle valve position into
output voltage, and emit the voltage signal to the ECM. In addition,
these sensors detect the opening and closing speed of the throttle
valve and feed the voltage signals to the ECM. The ECM judges the
current opening angle of the throttle valve from these signals and the
ECM controls the throttle control motor to make the throttle valve
opening angle properly in response to driving condition.

On Board Diagnosis Logic

INFOID:0000000001326305

The MIL will not light up for this self-diagnosis.

DTC Confirmation Procedure

INFOID:0000000001326306

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 10V at idle.
1.

Turn ignition switch ON.

2.

Turn ignition switch OFF and wait at least 10 seconds.

3.

Turn ignition switch ON.

4.

Repeat steps 2 and 3 for 32 times.

5.

Check 1st trip DTC.

6.

If 1st trip DTC is detected, go to 

EC-449, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000001326307

1.

CHECK ELECTRIC THROTTLE CONTROL ACTUATOR VISUALLY

1.

Turn ignition switch OFF.

2.

Remove the intake air duct.

3.

Check if foreign matter is caught between the throttle valve and
the housing.

OK or NG

OK

>> GO TO 2.

NG

>> Remove the foreign matter and clean the electric throttle

control actuator inside.

2.

REPLACE ELECTRIC THROTTLE CONTROL ACTUATOR

1.

Replace the electric throttle control actuator.

2.

Perform 

EC-85, "Throttle Valve Closed Position Learning"

.

PBIB0145E

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1226
1226

Closed throttle position 
learning performance

Closed throttle position learning is not per-
formed successfully, repeatedly.

• Electric throttle control actuator

(TP sensor 1 and 2)

PBIB1556E

EC-450

< SERVICE INFORMATION >

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DTC P1226 TP SENSOR

3.

Perform 

EC-85, "Idle Air Volume Learning"

.

>> INSPECTION END

Removal and Installation

INFOID:0000000001326308

ELECTRIC THROTTLE CONTROL ACTUATOR

Refer to 

EM-19

.

DTC P1421 COLD START CONTROL

EC-451

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DTC P1421 COLD START CONTROL

Description

INFOID:0000000001326309

ECM controls ignition timing and engine idle speed when engine is started with prewarming up condition.
This control promotes the activation of three way catalyst by heating the catalyst and reduces emissions.

On Board Diagnosis Logic

INFOID:0000000001326310

DTC Confirmation Procedure

INFOID:0000000001326311

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.

• If DTC P1421 is displayed with other DTC, first perform the trouble diagnosis for other DTC.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11V at idle.

 WITH CONSULT-III

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Select “DATA MONITOR” mode with CONSULT-III.

4.

Check that the “COOLAN TEMP/S” indication is between 4

°

C (39

°

F) and 36

°

C (97

°

F).

If “COOLAN TEMP/S” indication is within the specified value, go to the following step.
If “COOLANT TEMP/S” indication is out of the specified value, cool engine down or warm engine up and
go to step 1.

5.

Start engine and let it idle for 5 minutes.

6.

Check 1st trip DTC.

7.

If 1st trip DTC is detected, go to 

EC-451, "Diagnosis Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT-III” above.

Diagnosis Procedure

INFOID:0000000001326312

1.

PERFORM IDLE AIR VOLUME LEARNING

Perform 

EC-85, "Idle Air Volume Learning"

.

Is Idle Air Volume Learning carried out successfully?

Yes or No

Yes

>> GO TO 2.

No

>> Follow the instruction of Idle Air Volume Learning.

2.

CHECK INTAKE SYSTEM

Check for the cause of intake air volume lacking. Refer to the following.
• Crushed intake air passage
• Intake air passage clogging

OK or NG

OK

>> GO TO 3.

NG

>> Repair or replace malfunctioning part

3.

CHECK FUEL INJECTION SYSTEM FUNCTION

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1421
1421

Cold start emission reduction 
strategy monitoring

ECM does not control ignition timing and engine 
idle speed properly when engine is started with 
prewarming up condition.

• Lack of intake air volume
• Fuel injection system
• ECM

EC-452

< SERVICE INFORMATION >

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DTC P1421 COLD START CONTROL

Perform 

EC-274, "DTC Confirmation Procedure"

 in DTC P0171, P0174 FUEL INJECTION SYSTEM FUNC-

TION.
OK or NG

OK

>> GO TO 4.

NG

>> Go to 

EC-279, "Diagnosis Procedure"

.

4.

PERFORM DTC CONFIRMATION PROCEDURE

 With CONSULT-III

1.

Turn ignition switch ON.

2.

Select “SELF DIAG RESULTS” mode with CONSULT-III.

3.

Touch “ERASE”.

4.

Perform DTC Confirmation Procedure.
See 

EC-451, "DTC Confirmation Procedure"

.

5.

Is the 1st trip DTC P1421 displayed again?

 With GST

1.

Turn ignition switch ON.

2.

Select Service $04 with GST.

3.

Perform DTC Confirmation Procedure.
See 

EC-451, "DTC Confirmation Procedure"

.

4.

Is the 1st trip DTC P1421 displayed again?

Yes or No

Yes

>> GO TO 5.

No

>> INSPECTION END

5.

REPLACE ECM

1.

Replace ECM.

2.

Perform initialization of IVIS (NATS) system and registration of all IVIS (NATS) ignition key IDs.
Refer to 

BL-187, "ECM Re-Communicating Function"

.

3.

Perform 

EC-84, "VIN Registration"

.

4.

Perform 

EC-85, "Accelerator Pedal Released Position Learning"

.

5.

Perform 

EC-85, "Throttle Valve Closed Position Learning"

.

6.

Perform 

EC-85, "Idle Air Volume Learning"

.

>> INSPECTION END