3. Check Heated Oxygen Sensor 1 Circuit For Open And Short

1. Turn ignition switch OFF.
2. Disconnect corresponding heated oxygen sensor 1 (HO2S1) harness connector.
3. Disconnect ECM harness connector.
4. Check harness continuity between ECM terminal and HO2S1 terminal as follows.

   Refer to Wiring Diagram.

   Fig 1: Checking HO2S 1 Circuit For Open And Short

   Courtesy of NISSAN MOTOR CO., U.S.A.
   1. Continuity should exist. 
5. Check harness continuity between the following terminals and ground.

   Refer to Wiring Diagram.

   Fig 2: Checking HO2S 1 Circuit For Open And Short

   Courtesy of NISSAN MOTOR CO., U.S.A.
   1. Continuity should not exist. 
6. Check harness continuity between HO2S1 terminal 4 and ECM terminal 78.

   Continuity should exist. 

7. Also check harness for short to ground and 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.