Diagnosis Procedure

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

   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
   P0171	1	F23	3	F111	88	Existed
   			4		90
   			6		94
   P0174	2	F24	3		78
   			4		80
   			6		74

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

   DTC	A/F sensor 1			ECM		Continuity	Continuity
   	Bank	Connector	Terminal	Connector	Terminal
   P0171	1	F23	3	F111	88	Existed	Not existed
   			4		90
   			6		94
   P0174	2	F24	3		78
   			4		80
   			6		74

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.

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 ".

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 grounds. 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.

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

   Courtesy of NISSAN NORTH AMERICA, INC.

   Is the inspection result normal? 

   YES: GO TO 7.

   NO: Perform trouble diagnosis for fuel injector, refer to "DIAGNOSIS PROCEDURE ".

Refer to "INTERMITTENT INCIDENT ".

Is the inspection result normal? 

YES: Replace fuel injector. Refer to "REMOVAL AND INSTALLATION ".

NO: Repair or replace malfunctioning part.