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.

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
With CONSULT-III

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. With GST

Follow the procedure "With CONSULT-III" above.
Is 1st trip DTC detected?
YES >> Go to Diagnosis Procedure.
NO >> Inspection END

Diagnosis Procedure
1.PERFORM IDLE AIR VOLUME LEARNING
Perform See: Engine, Cooling and Exhaust\Engine\Idle Speed\Testing and Inspection\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 See: P0171 for DTC P0171, P0174.
Is the Inspection result normal?
YES >> GO TO 4.
NO >> Go to See: P0171 for DTC P0171, P0174.
4.PERFORM DTC CONFIRMATION PROCEDURE

1. Turn ignition switch ON.
2. Erase DTC.
3. Perform DTC CONFIRMATION PROCEDURE. See 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 See: Powertrain Management\Computers and Control Systems\Testing and Inspection\Programming and Relearning\Additional Service When Replacing Control Unit\Special Repair Requirement. >> Inspection END