Diagnostic Procedure

RETIGHTEN GROUND SCREWS
1. Turn ignition switch OFF.
2. Loosen and retighten engine ground screws.
  1. GO TO 2.
Fig 1: Identifying Engine Ground Screws
Courtesy of NISSAN MOTOR CO., U.S.A.
CLEAR THE SELF-LEARNING DATA
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 detected?
  
  Is it difficult to start engine?
  
  Fig 2: Displaying SELF-LEARNING CONT In WORK SUPPORT Mode
  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 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 detected?
  
  Is it difficult to start engine?
  
  Fig 3: 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. Refer to DTC P0171 FUEL INJECTION SYSTEM FUNCTION .
2. No: GO TO 3.
CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 2 harness connector.
3. Disconnect ECM harness connector.
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 short to ground and 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.
Fig 4: Disconnecting Heated Oxygen Sensor 2 Harness Connector
Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminal 74 and HO2S2 terminal 1.
  Refer to WIRING DIAGRAM .
  1. Continuity should exist.
2. Check harness continuity between ECM terminal 74 or HO2S2 terminal 1 and ground.
  Refer to WIRING DIAGRAM .
  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.
CHECK HEATED OXYGEN SENSOR 2
Refer to COMPONENT INSPECTION .

OK or NG
1. OK: GO TO 6.
2. NG: Replace heated oxygen sensor 2.
CHECK INTERMITTENT INCIDENT
Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .
1. INSPECTION END