3. Check Ho2S1 Ground Circuit For Open And Short

1. Disconnect heated oxygen sensor 1 harness connector.
   Fig 1: Identifying HO2S1 Harness Connector

   Courtesy of NISSAN MOTOR CO., U.S.A.
2. Check harness continuity between HO2S1 terminal 4 and ground.

   Continuity should exist. 

   Refer to WIRING DIAGRAM .

3. Also check harness for short to power.

OK or NG 

1. OK: GO TO 4.
2. NG: Repair open circuit or short to power in harness or connector.