Diagnostic Procedure

RETIGHTEN GROUND SCREWS
1. Turn ignition switch OFF.
2. Loosen and retighten engine ground screws.
  
  Fig 1: Identifying Engine Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
  1. GO TO 2.
RETIGHTEN AIR FUEL RATIO (A/F) SENSOR 1
Loosen and retighten the air fuel ratio (A/F) sensor 1.

Tightening torque: 40 - 60 N-m (4.1 - 6.1 kg-m, 30 - 44 ft-lb)
1. GO TO 3.
CHECK EXHAUST GAS LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust air leak before three way catalyst (manifold).
  
  Fig 2: Identifying Exhaust Air Leak
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
1. OK: GO TO 4.
2. NG: Repair or replace.
CHECK FOR INTAKE AIR LEAK
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.
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" or "START".
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?
  
  Fig 3: Displaying 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 3 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 P0172 detected? Is it difficult to start engine?
  
  Fig 4: 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, P0172. Refer to DTC P0171 FUEL INJECTION SYSTEM FUNCTION , DTC P0172 FUEL INJECTION SYSTEM FUNCTION .
2. No: GO TO 6.
CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector and A/F sensor 1 harness connector.
3. Check harness continuity between the following terminals. Refer to WIRING DIAGRAM .
  
  Fig 5: Disconnecting ECM & A/F Sensor 1 Terminals Table
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Fig 6: Disconnecting A/F Sensor 1 Harness Connector
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Continuity should exist.
4. Check harness continuity between ECM terminals 16, 35, 56, 75 or A/F sensor 1 terminals 1, 2, 5, 6 and ground. Refer to WIRING DIAGRAM .
  Continuity should not exist.
5. Also check harness for 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.
CHECK AIR FUEL RATIO (A/F) SENSOR 1 HEATER
Refer to "COMPONENT INSPECTION ".

OK or NG
1. OK: GO TO 8.
2. NG: Replace A/F sensor 1.
CHECK MASS AIR FLOW SENSOR
Refer to "COMPONENT INSPECTION ".

OK or NG
1. OK: GO TO 9.
2. NG: Replace mass air flow sensor.
CHECK PCV VALVE
Refer to "POSITIVE CRANKCASE VENTILATION " .

OK or NG
1. OK: GO TO 10.
2. NG: Repair or replace PCV valve.
CHECK INTERMITTENT INCIDENT
Perform "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

OK or NG
1. OK: Replace A/F sensor 1.
2. NG: Repair or replace.