Diagnosis Procedure

1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst 1.
   Fig 1: Checking Exhaust Gas Leak

   Courtesy of NISSAN MOTOR CO., U.S.A.

Is exhaust gas leak detected? 

YES: Repair or replace malfunctioning part.

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 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.
   CONTINUITY SPECIFICATIONS
   
   

   DTC	A/F sensor 1			ECM		Continuity
   	Bank	Connector	Terminal	Connector	Terminal
   P0172	1	F3	1	F102	57	Existed
   			2		61
   P0175	2	F20	1		65
   			2		66

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

   DTC	A/F sensor 1			ECM		Ground	Continuity
   	Bank	Connector	Terminal	Connector	Terminal
   P0172	1	F3	1	F102	57	Ground	Not existed
   			2		61
   P0175	2	F20	1		65
   			2		66

6. Also check harness for short to power.

Is the inspection result normal? 

YES: GO TO 4.

NO: Repair open circuit or short to ground or short to power in harness or connectors.

Check fuel pressure. Refer to "INSPECTION ".

Is the inspection result normal? 

YES: GO TO 5.

NO: Replace "fuel filter and fuel pump assembly".

With CONSULT-III 

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

   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 "DIAGNOSIS PROCEDURE ".

With CONSULT-III 

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

Without CONSULT-III 

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

   Clicking sound should be heard. 

Is the inspection result normal? 

YES: GO TO 7.

NO: Perform trouble diagnosis for FUEL INJECTOR, refer to "DIAGNOSIS PROCEDURE ".

Fig 2: Checking Function Of Fuel Injector

Courtesy of NISSAN MOTOR CO., U.S.A.

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 injectors.
6. Crank engine for about 3 seconds.

   Check fuel does not drip from fuel injector.

Is the inspection result normal? 

YES: GO TO 8.

NO: Replace the fuel injectors from which fuel is dripping. Always replace O-ring with new one.

Refer to "INTERMITTENT INCIDENT ".

INSPECTION END