Diagnosis Procedure

1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst 1.

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Is exhaust gas leak detected?

YES

Repair or replace error-detected parts.

NO

GO TO 2.

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

Is intake air leak detected?

YES

Repair or replace error-detected parts.

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	+			-		Continuity
   	A/F sensor 1			ECM
   	Bank	Connector	Terminal	Connector	Terminal
   P0171	1	F133	3	F142	102	Existed
   			4		101
   P0174	2	F134	3		111
   			4		107

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

   DTC	+			-	Continuity
   	A/F sensor 1
   	Bank	Connector	Terminal
   P0171	1	F133	3	Ground	Not existed
   			4
   P0174	2	F134	3
   			4

   DTC	+			-	Continuity
   	ECM
   	Bank	Connector	Terminal
   P0171	1	F142	101	Ground	Not existed
   			102
   P0174	2		107
   			111

6. Also check harness for short to power.

Is the inspection result normal?

YES

GO TO 4.

NO

Repair or replace error-detected parts.

1. Release fuel pressure to zero. Refer to Work Procedure .
2. Install fuel pressure gauge and check fuel pressure. Refer to Work Procedure .

Is the inspection result normal?

YES

GO TO  6.

NO

GO TO 5.

Check fuel hoses and fuel tubes for clogging.

Is the inspection result normal?

YES

Replace "fuel filter and fuel pump assembly". Refer to Removal and Installation .

NO

Repair or replace error-detected parts.

With CONSULT

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

   For specification, refer to Mass Air Flow Sensor .

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 .

Is the measurement value within the specification?

YES

GO TO 7.

NO

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

With CONSULT

1. Start engine.
2. Perform "POWER BALANCE" in "ACTIVE TEST" mode with CONSULT.
3. Make sure 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

INSPECTION END

NO

Perform trouble diagnosis for FUEL INJECTOR, refer to Diagnosis Procedure .