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 Harness Continuity Between ECM Terminal & HO2S1 Terminal

   Courtesy of NISSAN MOTOR CO., U.S.A.

   Continuity should exist. 

5. Check harness continuity between the following terminals and ground. Refer to WIRING DIAGRAM .
   Fig 2: Checking Harness Continuity Between Terminals & Ground

   Courtesy of NISSAN MOTOR CO., U.S.A.

   Continuity should not exist. 

6. Check harness continuity between HO2S1 terminal 4 and ground.

   Continuity should exist. 

7. Also check harness for short to power.

OK or NG 

1. OK: GO TO 5. CHECK FUEL PRESSURE .
2. NG: GO TO 4.