DTC Diagnosis Procedure

1. Start engine and run it at idle.
2. Listen for an exhaust gas leakage before three way catalyst (manifold).

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Is exhaust gas leakage detected?

YES

Repair or replace malfunctioning part.

NO

GO TO 2.

1. Listen for an intake air leakage after the mass air flow sensor.
2. Check PCV hose connection.

Is intake air leakage detected?

YES

Repair or replace malfunctioning part.

NO

GO TO 3.

1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

   DTC	A/F sensor 1			ECM		Continuity
   	Bank	Connector	Terminal	Connector	Terminal
   P0171	1	F133	1	F92	79	Existed
   			2		74
   P0174	2	F134	1	F92	69
   			2		70

5. Check the continuity between A/F sensor 1 harness connector and ground, or ECM harness connector and ground.

   DTC	A/F sensor 1			Ground	Continuity
   	Bank	Connector	Terminal
   P0171	1	F133	1	Ground	Not Existed
   			2
   P0174	2	F134	1
   			2

   DTC	ECM			Ground	Continuity
   	Bank	Connector	Terminal
   P0171	1	F92	79	Ground	Not Existed
   			74
   P0174	2	F92	69
   			70

6. Also check harness for short to power.

Is the inspection result normal?

YES

GO TO 4.

NO

Repair open circuit, short to ground or short to power in harness or connectors.

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure 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 5.

1. Clear the mixture ratio self-learning value. Refer to Work Procedure .
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Start engine and keep the engine speed between 3, 500 and 4, 000 RPM for 1 minute under no load.
6. Let engine idle for 1 minute.
7. Keep engine speed between 2, 500 and 3, 000 RPM for 20 minutes.
8. Check 1st trip DTC.

Is 1st trip DTC detected?

YES

Replace A/F sensor.

NO

GO TO 6.

Check fuel pressure. Refer to Work Procedure .

Is the inspection result normal?

YES

GO TO 8.

NO

GO TO 7.

Check fuel hoses and fuel tubes for clogging.

Is the inspection result normal?

YES

Replace "fuel filter and fuel pump assembly". Refer to FUEL LEVEL SENSOR UNIT, FUEL FILTER AND FUEL PUMP ASSEMBLY : Removal & Installation .

NO

Repair or replace malfunctioning part.

WITH CONSULT

1. Install all removed parts.
2. Check "MASS AIR FLOW" in "DATA MONITOR" mode with CONSULT.

   For specification, Refer to MASS AIR FLOW SENSOR : Service Data .

WITH GST

1. Install all removed parts.
2. Check mass air flow sensor signal in Service $01 with GST.

   For specification, Refer to MASS AIR FLOW SENSOR : Service Data .

Is the measurement value within the specification?

YES

GO TO 9.

NO

Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or grounds. Refer to DTC Diagnosis Procedure .

WITH CONSULT

1. Start engine.
2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT.
3. Check that each circuit produces a momentary engine speed drop.

WITHOUT CONSULT

1. Start engine and let it idle.
2. Listen to each fuel injector operating sound.

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   Clicking sound should be heard.

Is the inspection result normal?

YES

GO TO 10.

NO

Perform trouble diagnosis for fuel injector, Refer to Diagnosis Procedure .

Refer to Inspection .

Is the inspection result normal?

YES

Replace fuel injector. Refer to FUEL INJECTOR AND FUEL TUBE : Removal & Installation .

NO

Repair or replace malfunctioning part.