Diagnostic Procedure

RETIGHTEN HEATED OXYGEN SENSOR 1
1. Turn ignition switch OFF.
2. Loosen and retighten heated oxygen sensor 1.
  
  Fig 1: Identifying Heated Oxygen Sensor 1
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Tightening torque: 40 - 60 N.m (4.1 - 6.1 kg-m, 30 - 44 ft-lb)
  1. GO TO 2.
CHECK HO2S1 GROUND CIRCUIT FOR OPEN AND SHORT
1. Disconnect heated oxygen sensor 1 harness connector.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 78 and HO2S1 terminal 4.
  Refer to WIRING DIAGRAM .
  
  Continuity should exist.
4. Also check harness for short to ground and short to power.
Fig 2: Identifying Heated Oxygen Sensor 1 Harness Connector
Courtesy of NISSAN MOTOR CO., U.S.A.

OK or NG
1. OK: GO TO 3.
2. NG: Repair open circuit or short to ground short to power in harness or connectors.
CHECK HO2S1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminal 35 and HO2S1 terminal 1. Refer to WIRING DIAGRAM .
  Continuity should exist.
2. Check harness continuity between ECM terminal 35, HO2S1 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 HO2S1 CONNECTOR FOR WATER
Check connectors for water.

Water should not exist.

OK or NG
1. OK: GO TO 5.
2. NG: Repair or replace harness or connectors.
CHECK HEATED OXYGEN SENSOR 1
Refer to "COMPONENT INSPECTION ".

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