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, P0174. Refer to DTC LOGIC .

Is the inspection result normal? 

YES: GO TO  4.

NO: Go to DIAGNOSIS PROCEDURE for DTC P0171, P0174.

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. Perform ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT (ECM): SPECIAL REPAIR REQUIREMENT .

   INSPECTION END