DTC DETECTION LOGIC NOTE：

- If DTC P1421 is displayed with other DTC, first perform the trouble diagnosis for other DTC.

DTC No. | Trouble diagnosis name | DTC detecting condition | Possible cause
P1421 | Cold start emission reduction strategy monitoring | ECM does not control ignition timing and engine idle speed properly when engine is started with pre-warming up condition. |

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

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 OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Select “DATA MONITOR” mode with CONSULT-III.
4. Check the indication of “COOLAN TEMP/S”.If it is between 4 °C (39 °F) and 36 °C (97 °F), go to the following steps.If it is below 4 °C (39 °F), warm engine up to more than 4 °C (39 °F) and retry from step 1.If it is above 36 °C (97 °F), cool engine down to less than 36 °C (97 °F) and retry from step 1.
5. Start engine and let it idle for 5 minutes.
6. Check 1st trip DTC.

Is 1st trip DTC detected?
YES>>Go to Diagnosis Procedure (GT-R certified NISSAN dealer).
NO>>INSPECTION END