Diagnostic Procedure

1. Turn ignition switch OFF.
2. Loosen and retighten two ground screws on the body. Refer to GROUND INSPECTION .
   Fig 1: Locating Ground Screws

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

OK or NG 

• OK : GO TO 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.
   Fig 2: CONSULT-II Display - WORK SUPPORT Mode

   Courtesy of NISSAN MOTOR CO., U.S.A.
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 or P0172 detected? 

   Is it difficult to start engine? 

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.
   Fig 3: Disconnecting Mass Air Flow Sensor Harness Connector

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure that DTC P0102 is displayed.
6. Erase the DTC memory. Refer to "HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION ".
7. Make sure that DTC P0000 is displayed.
8. Run engine for at least 10 minutes at idle speed.

   Is the 1st trip DTC P0171 or P0172 detected? 

   Is it difficult to start engine? 

Yes or No 

• Yes : Perform trouble diagnosis for DTC P0171 or P0172. Refer to "DTC P0171 FUEL INJECTION SYSTEM FUNCTION " or "DTC P0172 FUEL INJECTION SYSTEM FUNCTION ".
• No : GO TO 3.

1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 2 harness connector.
3. Disconnect ECM harness connector.
   Fig 4: Disconnecting Heated Oxygen Sensor 2 Harness Connector

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. Check harness continuity between ECM terminal 78 and HO2S2 terminal 4.

   Refer to WIRING DIAGRAM .

   • Continuity should exist. 
5. Also check harness for short to ground and 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. Check harness continuity between ECM terminal 74 and HO2S2 terminal 1. Refer to WIRING DIAGRAM .
   • Continuity should exist. 
2. Check harness continuity between ECM terminal 74 or HO2S2 terminal 1 and ground. Refer to WIRING DIAGRAM .
   • Continuity should not exist. 
3. Also check harness for short to power.

OK or NG 

• OK : GO TO 5.
• NG : Repair open circuit or short to ground or short to power in harness or connectors.

Refer to "COMPONENT INSPECTION ".

OK or NG 

• OK : GO TO 6.
• NG : Replace heated oxygen sensor 2.

Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

• : INSPECTION END