Diagnostic Procedure

CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to GROUND INSPECTION .
  
  Fig 1: Tightening Ground Screws On Body
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
- OK: GO TO 2.
- NG: Repair or replace ground connections.
CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT
1. Disconnect heated oxygen sensor 2 harness connector.
  
  Fig 2: Locating Heated Oxygen Sensor 2 Harness Connectors
  Courtesy of NISSAN MOTOR CO., U.S.A.
2. Disconnect ECM harness connector.
3. Check harness continuity between HO2S2 terminal 4 and ECM terminal 78.
  Refer to WIRING DIAGRAM .
  - Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
- OK: GO TO 3.
- NG: Repair open circuit or short to ground or short to ground or short to power in harness or connectors.
CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminal and HO2S2 terminal as follows.
  Refer to WIRING DIAGRAM .
  
  Fig 3: ECM Terminal And HO2S Terminal Reference Chart (1 Of 2)
  Courtesy of NISSAN MOTOR CO., U.S.A.
  - Continuity should exist.
2. Check harness continuity between the following terminals and ground.
  Refer to WIRING DIAGRAM .
  
  Fig 4: ECM Terminal And HO2S Terminal Reference Chart (2 Of 2)
  Courtesy of NISSAN MOTOR CO., U.S.A.
  - Continuity should not exist.
3. Also check harness for 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.
CHECK HO2S2 CONNECTOR FOR WATER
Check connectors for water.
- Water should not exist.
OK or NG
- OK: GO TO 5.
- NG: Repair or replace harness or connectors.
CHECK HEATED OXYGEN SENSOR 2
Refer to COMPONENT INSPECTION .

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