Diagnostic Procedure

RETIGHTEN GROUND SCREWS
1. Turn ignition switch OFF.
2. Loosen and retighten engine ground screws.
  1. GO TO 2.
    
    Fig 1: Loosening And Retighten 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 or P0174 detected?
  
  Is it difficult to start engine?
  
  Fig 2: Displaying "SELF-LEARNING CONT" In "WORK SUPPORT" Mode With CONSULT-II
  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.
  Is the 1st trip DTC P0171 or P0174 detected?
  
  Is it difficult to start engine?
  
  Fig 3: Disconnect 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 or P0174. Refer to DTC P0171, P0174 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.
  
  Fig 4: Disconnecting Heated Oxygen Sensor 2 Harness Connector
  Courtesy of NISSAN MOTOR CO., U.S.A.
3. Check harness continuity between HO2S2 terminal 4 and engine ground.
  Refer to WIRING DIAGRAM .
  
  Continuity should exist.
4. Also check harness for short to power.
OK or NG
1. OK: GO TO 5.
2. NG: GO TO 4.
DETECT MALFUNCTIONING PART
Check the following.
- Joint connector-2
- Harness for open or short between HO2S2 and engine ground
  1. Repair open circuit or short to power in harness or connectors.
CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal and HO2S2 terminal as follows.
  Refer to WIRING DIAGRAM .
  
  Fig 5: Terminal Continuity Chart
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Continuity should exist.
3. Check harness continuity between the following terminals and ground.
  Refer to WIRING DIAGRAM .
  
  Fig 6: Terminal And Continuity Chart
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Continuity should not exist.
4. Also check harness for short to power.
OK or NG
1. OK: GO TO 6.
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 7.
2. NG: Replace malfunctioning heated oxygen sensor 2.
CHECK INTERMITTENT INCIDENT
Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".
1. INSPECTION END