Diagnosis Procedure

Perform , "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.

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

Perform DTC CONFIRMATION PROCEDURE for DTC P0171. Refer to , "DTC LOGIC ".

Is the inspection result normal? 

YES: GO TO 4.

NO: Go to "DIAGNOSIS PROCEDURE " for DTC P0171.

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

1. Replace ECM.
2. Go to , "ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT : SPECIAL REPAIR REQUIREMENT ".

INSPECTION END