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 Retightening Engine Ground Screws
Courtesy of NISSAN MOTOR CO., U.S.A.
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 3.
2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
Fig 2: 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 .
  
  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
1. OK: GO TO 4.
2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
CHECK HARNESS CONNECTOR
Check HO2S2 harness connector for water.

Water should not exist.

OK or NG
1. OK: GO TO 5.
2. NG: Repair or replace harness connector.
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