Diagnostic Procedure

1. Turn ignition switch OFF.
2. Loosen and retighten ground three screws on the body. Refer to GROUND INSPECTION  .
   Fig 1: Checking Ground Connections

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

OK or NG 

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

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.

   Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected? 

   Is it difficult to start engine? 

   Fig 2: Displaying Work Support Screen

   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.
4. Restart engine and let it idle for at least 5 seconds.
5. Stop engine and reconnect mass air flow sensor harness connector.
6. Make sure DTC P0102 is displayed.
7. Erase the DTC memory. Refer to HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION  .
8. Make sure DTC P0000 is displayed.
9. Run engine for at least 10 minutes at idle speed.

   Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected? 

   Is it difficult to start engine? 

   Fig 3: Reconnecting 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 P0172, P0175. Refer to DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION  or DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION  .
2. No: GO TO 3.

1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Disconnect heated oxygen sensor 2 harness connector.
   Fig 4: Checking HO2S2 Ground Circuit For Open And Short

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. Check harness continuity between ECM terminal 78 and HO2S2 terminal 4. Refer to WIRING DIAGRAM  .
   1. Continuity should exist. 
5. Also check harness for shirt to ground or short to power.

OK or NG 

1. OK: GO TO 4.
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 HO2S2 terminal as follows. Refer to WIRING DIAGRAM  .
   Fig 5: Terminals, DTC And Bank Chart

   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 6: Terminals, DTC And Bank Chart

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

OK or NG 

1. OK: GO TO 5.
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 6.
2. NG: Replace malfunctioning heated oxygen sensor 2.

Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT  .

1. INSPECTION END