Diagnosis Procedure

1. CHECK EXHAUST GAS LEAK
   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 Before Three Way Catalyst 1

      Courtesy of NISSAN NORTH AMERICA, INC.

      Is exhaust gas leak detected? 

      YES: Repair or replace malfunctioning part.

      NO: GO TO 2.

2. CHECK FOR INTAKE AIR LEAK
   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 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.

      DTC	A/F sensor 1			ECM		Continuity
      	Bank	Connector	Terminal	Connector	Terminal
      P0171	1	F66	1	F102	57	Existed
      			2		61
      P0174	2	F67	1		65
      			2		66

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

      DTC	A/F sensor 1			Ground	Continuity
      	Bank	Connector	Terminal
      P0171	1	F66	1	Ground	Not existed
      			2
      P0174	2	F67	1
      			2

      DTC	ECM		Ground	Continuity
      	Connector	Terminal
      P0171	F102	57	Ground	Not existed
      		61
      P0174		65
      		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.

4. CHECK FUEL PRESSURE

   Check fuel pressure. Refer to "INSPECTION ".

   Is the inspection result normal? 

   YES: GO TO  6.

   NO: GO TO 5.

5. DETECT MALFUNCTIONING PART

   Check fuel hoses and fuel tubes for clogging.

   Is the inspection result normal? 

   YES: Replace "fuel filter and fuel pump assembly". Refer to "EXPLODED VIEW ".

   NO: Repair or replace malfunctioning part.

6. CHECK MASS AIR FLOW SENSOR

   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 7.

      NO: Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or grounds. Refer to "DIAGNOSIS PROCEDURE ".

7. CHECK FUNCTION OF FUEL INJECTOR

   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.

   Without CONSULT 

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

      Clicking sound should be heard. 

      Fig 2: Checking Fuel Injector Operating Sound

      Courtesy of NISSAN NORTH AMERICA, INC.

      Is the inspection result normal? 

      YES: GO TO 8.

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

8. CHECK FUEL INJECTOR
   1. Turn ignition switch OFF.
   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. Remove fuel tube assembly. Refer to "REMOVAL AND INSTALLATION ".

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

   5. For DTC P0171, reconnect fuel injector harness connectors on bank 1.

      For DTC P0174, reconnect fuel injector harness connectors on bank 2.

   6. Disconnect all ignition coil harness connectors.
   7. Prepare pans or saucers under each fuel injector.
   8. Crank engine for about 3 seconds.

      For DTC P0171, check that fuel sprays out from fuel injectors on bank 1.

      For DTC P0174, check that fuel sprays out from fuel injectors on bank 2.

      Fuel should be sprayed evenly for each fuel injector. 

      Fig 3: Checking Fuel Injector Spraying Manner

      Courtesy of NISSAN NORTH AMERICA, INC.

      Is the inspection result normal? 

      YES: GO TO 9.

      NO: Replace fuel injectors from which fuel does not spray out. Always replace O-ring with new ones. Refer to "REMOVAL AND INSTALLATION ".

9. CHECK INTERMITTENT INCIDENT

   Refer to "INTERMITTENT INCIDENT ".

INSPECTION END