Diagnostic Procedure

1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.

   Refer to "GROUND INSPECTION ".

   Fig 1: Identifying Connections Ground

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

OK or NG 

1. OK: GO TO 2.
2. NG: Repair or replace ground connections.

Loosen and retighten heated oxygen sensor 1.

Fig 2: Tightening Torque Heated Oxygen Sensor 1

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

1. Tightening torque: 40 - 60 N.m (4.1 - 6.1 kg-m, 30 - 44 ft-lb) 
2. GO TO 3.

1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst (manifold).
   Fig 3: Checking Exhaust Gas Leak

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

OK or NG 

1. OK: GO TO 4.
2. NG: Repair or replace.

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

OK or NG 

1. OK: GO TO 5.
2. NG: Repair or replace.

With CONSULT-II 

1. Start engine and warm it up to normal operating temperature.
2. Select "SELF-LEARNING CONT" in "WORK SUPPORT" mode with CONSULT-II.
3. Clear the self-learning control coefficient by touching "CLEAR".
4. Run engine for at least 10 minutes at idle speed.
   1. Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected? Is it difficult to start engine? 
   Fig 4: Work Support Mode With CONSULT-II Display

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

Without CONSULT-II 

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF.
3. Disconnect mass air flow sensor harness connector, and restart and run engine for at least 5 seconds at idle speed.
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure DTC P0102 is displayed.
6. Erase the DTC memory. Refer to "HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION ".
7. Make sure DTC P0000 is displayed.
8. Run engine for at least 10 minutes at idle speed.
   1. Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected? Is it difficult to start engine? 
   Fig 5: Disconnecting Mass Air Flow Sensor Harness Connector

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

Yes or No 

1. Yes: Perform trouble diagnosis for DTC P0171, P0174 or DTC P0172, P0175 (Refer to DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION  or DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION ).
2. No: GO TO 6.

1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 1 harness connector.
   Fig 6: Disconnecting Heated Oxygen Sensor 1 Harness Connector

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. Disconnect ECM harness connector.
4. Check harness continuity between HO2S1 terminal 4 and ECM terminal 78. Refer to WIRING DIAGRAM .
   1. Continuity should exist. 
5. Also check harness for short to ground and short to power.

OK or NG 

1. OK: GO TO 7.
2. NG: Repair open circuit or short to ground or short to power in harness or connectors.

1. Check harness continuity between ECM terminal and HO2S1 terminal as follows. Refer to WIRING DIAGRAM .
   Fig 7: DTC Continuity Between ECM Terminal

   Courtesy of NISSAN MOTOR CO., U.S.A.
   1. Continuity should exist. 
2. Check harness continuity between the following terminals and ground. Refer to WIRING DIAGRAM .
   Fig 8: DTC Continuity Between ECM Terminal

   Courtesy of NISSAN MOTOR CO., U.S.A.
   1. Continuity should not exist. 
3. Also check harness for short to ground and short to power.

OK or NG 

1. OK: GO TO 8.
2. NG: Repair open circuit or short to ground or short to power in harness or connectors.

Refer to "COMPONENT INSPECTION ".

OK or NG 

1. OK: GO TO 9.
2. NG: Replace mass air flow sensor.

Refer to "COMPONENT INSPECTION ".

OK or NG 

1. OK: GO TO 10.
2. NG: Replace PCV valve.

Refer to "COMPONENT INSPECTION ".

OK or NG 

1. OK: GO TO 11.
2. NG: Replace malfunctioning heated oxygen sensor 1.

Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

1. INSPECTION END