Diagnosis Procedure

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

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

OK or NG 

OK: GO TO 2.

NG: Repair or replace.

1. Listen for an intake air leak after the mass air flow sensor.
2. Check PCV hose connection.

OK or NG 

OK: GO TO 3.

NG: Repair or replace.

1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
   Fig 2: Identifying A/F Sensor 1 Harness Connector

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. Disconnect ECM harness connector.
4. Check harness continuity between the following terminals.

   Refer to WIRING DIAGRAM .

   CONTINUITY REFERENCE CHART
   
   

   	A/F sensor 1 terminal	ECM terminal
   Bank 1	1	35
   	2	56
   Bank 2	1	16
   	2	75

   Continuity should exist. 

5. Check harness continuity between the following terminals and ground.

   Refer to WIRING DIAGRAM .

   CONTINUITY REFERENCE CHART
   
   

   Bank 1		Bank 2
   A/F sensor 1 terminal	ECM terminal	A/F sensor 1 terminal	ECM terminal
   1	35	1	16
   2	56	2	75

   Continuity should not exist. 

6. Also check harness for short to power.

OK or NG 

OK: GO TO 4.

NG: Repair open circuit or short to ground or short to power in harness or connectors.

1. Release fuel pressure to zero. Refer to "FUEL PRESSURE CHECK ".
2. Install fuel pressure gauge and check fuel pressure. Refer to "FUEL PRESSURE CHECK ".

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

OK or NG 

OK: GO TO  6.

NG: GO TO 5.

Check the following.

• Fuel pump and circuit (Refer to "DIAGNOSIS PROCEDURE ".)
• Fuel pressure regulator (Refer to "FUEL PRESSURE CHECK ".)
• Fuel lines
• Fuel filter for clogging

Repair or replace.

With CONSULT-III 

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

   3.0 - 9.0 g.m/sec: at idling 

   9.0 - 28.0 g.m/sec: at 2, 500 RPM 

With GST 

1. Install all removed parts.
2. Check mass air flow sensor signal in Service $01 with GST.

   3.0 - 9.0 g.m/sec: at idling 

   9.0 - 28.0 g.m/sec: at 2, 500 RPM 

OK or NG 

OK: GO TO 7.

NG: Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or grounds. Refer to P0101 MAF SENSOR .

With CONSULT-III 

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

Without CONSULT-III 

1. Start engine.
2. Listen to each fuel injector operating sound.

   Clicking noise should be heard. 

OK or NG 

OK: GO TO 8.

NG: Perform trouble diagnosis for FUEL INJECTOR, refer to "DIAGNOSIS PROCEDURE ".

Fig 3: Checking Fuel Injector

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

1. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
2. Turn ignition switch OFF.
3. Disconnect all fuel injector harness connectors.
4. Remove fuel injector gallery assembly. Refer to "REMOVAL AND INSTALLATION ".

   Keep fuel hose and all fuel injectors connected to fuel injector gallery.

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, make sure that fuel sprays out from fuel injectors on bank 1.

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

   Fuel should be sprayed evenly for each fuel injector. 

   Fig 4: Checking Fuel Injector

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

OK or NG 

OK: GO TO 9.

NG: Replace fuel injectors from which fuel does not spray out. Always replace O-ring with new ones.

Refer to "HOW TO CHECK TERMINAL " and "INTERMITTENT INCIDENT ".

INSPECTION END