Diagnosis Procedure

Regarding Wiring Diagram information, refer to "WIRING DIAGRAM-ENGINE CONTROL SYSTEM- ".

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

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

      Is exhaust gas leakage detected? 

      YES: Repair or replace malfunctioning part.

      NO: GO TO  2.

2. CHECK FOR INTAKE AIR LEAKAGE

   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.

3. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT
   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.
      CONNECTOR TERMINAL CONTINUITY CHART
      
      

      DTC	A/F sensor 1			ECM		Continuity
      	Bank	Connector	Terminal	Connector	Terminal
      P0172	1	F12	1	F13	45	Existed
      			2		49
      P0175	2	F61	1		53
      			2		57

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

      DTC	A/F sensor 1			Ground	Continuity
      	Bank	Connector	Terminal
      P0172	1	F12	1	Ground	Not existed
      			2
      P0175	2	F61	1
      			2

      CONNECTOR TERMINAL CONTINUITY CHART
      
      

      DTC	ECM		Ground	Continuity
      	Connector	Terminal
      P0172	F13	45	Ground	Not existed
      		49
      P0175		53
      		57

   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.

4. CHECK FUEL PRESSURE
   1. Release fuel pressure to zero. Refer to "INSPECTION ".
   2. Install fuel pressure gauge kit [SST (J-44321)] and check fuel pressure. Refer to "INSPECTION ".

      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".

5. CHECK MASS AIR FLOW SENSOR

   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 ground. Refer to "DIAGNOSIS PROCEDURE ".

6. CHECK FUNCTION OF FUEL INJECTOR

   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.

   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 MOTOR CO., U.S.A.
7. CHECK FUEL INJECTOR
   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.

      Check that 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.

8. CHECK INTERMITTENT INCIDENT

   Refer to INTERMITTENT INCIDENT .

   INSPECTION END