Diagnosis Procedure

1. Start engine and run it at idle.
2. Listen for an exhaust gas leakage before three way catalyst (manifold).
   Fig 1: Checking Exhaust Gas Leakage

   Courtesy of NISSAN NORTH AMERICA, INC.

   Is exhaust gas leakage detected? 

   YES: Repair or replace malfunctioning part.

   NO: GO TO 2.

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

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
   P0172	1	F27	1	F8	69	Existed
   			2		73
   P0175	2	F64	1		77
   			2		81

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
   P0172	1	F27	1	Ground	Not existed
   			2
   P0175	2	F64	1
   			2

   DTC	ECM		Ground	Continuity
   	Connector	Terminal
   P0172	F8	69	Ground	Not existed
   		73
   P0175		77
   		81

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.

1. Release fuel pressure to zero. Refer to "WORK PROCEDURE ".
2. Install fuel pressure gauge kit [SST: - (J-44321)] and check fuel pressure. Refer to "WORK PROCEDURE ".

   At idling: Approximately 350 kPa (3.57 kg/cm ²  , 51 psi) 

   Is the inspection result normal? 

   YES: GO TO 5.

   NO: Replace "fuel filter and fuel pump assembly". Refer to "EXPLODED VIEW ".

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 ".

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 ground. Refer to "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.

With GST 

1. Let engine idle.
2. Listen to each fuel injector operating sound.

   Is the inspection result normal? 

   YES: GO TO 7.

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

   Fig 2: Checking Fuel Injector Operating Sound

   Courtesy of NISSAN NORTH AMERICA, INC.

1. Remove fuel injector assembly. Refer to "EXPLODED VIEW ".

   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: 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 "EXPLODED VIEW ".