DTC Diagnosis Procedure

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

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Is exhaust gas leak detected?

YES

Repair or replace error-detected parts.

NO

GO TO 2.

Listen for an intake air leak after the mass air flow sensor.

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.

   +			-		Continuity
   A/F sensor 1			ECM
   Bank	Connector	Terminal	Connector	Terminal
   1	F65	3	F77	66	Existed
   		4		67

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

   +			-	Continuity
   A/F sensor 1			Ground
   Bank	Connector	Terminal
   1	F65	3	Ground	Not existed
   		4

   +			-	Continuity
   ECM			Ground
   Bank	Connector	Terminal
   1	F77	66	Ground	Not existed
   		67

6. Also check harness for short to power.

Is the inspection result normal?

YES

GO TO 4.

NO

Repair or replace error-detected parts.

Check fuel pressure. Refer to Work Procedure .

Is the inspection result normal?

YES

GO TO 5.

NO

Replace "fuel filter and fuel pump assembly". Refer to Removal and Installation - VQ40DE .

With CONSULT

1. Install all removed parts.
2. Check "MASS AIR FLOW" in "DATA MONITOR" mode of "ENGINE" using 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 6.

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 of "ENGINE" using 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

GO TO 7.

NO

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

1. Remove fuel injector assembly. Refer to Removal and Installation .

   Keep fuel hose and all fuel injectors connected to fuel tube.

2. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
3. Disconnect all fuel injector harness connectors.
4. Disconnect all ignition coil harness connectors.
5. Prepare pans or saucers under each fuel injector.
6. Crank engine for about 3 seconds.

   Make sure fuel that does not drip from fuel injector.

Is the inspection result normal?

YES

Check intermittent incident. Refer to Intermittent Incident .

NO

Replace the fuel injectors from which fuel is dripping. Always replace O-ring with new one. Refer to Removal and Installation .