Nissan Altima 2007-2012 Service Manual: P1421 Cold start control

Description

ECM controls ignition timing and engine idle speed when engine is started with pre-warming up condition.

This control promotes the activation of three way catalyst by heating the catalyst and reduces emissions.

DTC Logic

DTC DETECTION LOGIC

NOTE: • If DTC P1421 is displayed with other DTC, first perform the trouble diagnosis for other DTC.

DTC CONFIRMATION PROCEDURE

1.PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next test.

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 11 V at idle.

>> GO TO 2.

2.PERFORM DTC CONFIRMATION PROCEDURE

1. Turn ignition switch ON.

2. Select “DATA MONITOR” mode with CONSULT-III.

3. 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 steps.

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

4. Start engine and let it idle for 5 minutes.

5. Check 1st trip DTC.

Follow the procedure “With CONSULT-III” above.

Is 1st trip DTC detected? YES >> Go to EC-1396, "Diagnosis Procedure".

NO >> INSPECTION END

Diagnosis Procedure

1.PERFORM IDLE AIR VOLUME LEARNING

Perform EC-1053, "IDLE AIR VOLUME LEARNING : Special Repair Requirement".

Is Idle Air Volume Learning carried out successfully? 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

Is the inspection result normal? YES >> GO TO 3.

NO >> Repair or replace malfunctioning part

3.CHECK FUEL INJECTION SYSTEM FUNCTION

Perform EC-1266, "DTC Logic" for DTC P0171, P0174.

Is the inspection result normal? YES >> GO TO 4.

NO >> Go to EC-1267, "Diagnosis Procedure" for DTC P0171, P0174.

4.PERFORM DTC CONFIRMATION PROCEDURE

1. Turn ignition switch ON.

2. Erase DTC.

3. Perform DTC CONFIRMATION PROCEDURE.

See EC-1396, "DTC Logic".

Is the 1st trip DTC P1421 displayed again? YES >> GO TO 5.

NO >> INSPECTION END

5.REPLACE ECM

1. Replace ECM.

2. Go to EC-1051, "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT : Special Repair Requirement".

>> INSPECTION END

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