3. Check Ho2S1 Input Signal Circuit For Open And Short

1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal and HO2S1 terminal as follows.
   Fig 1: Checking Harness Continuity Between ECM Terminal & HO2S1 Terminal

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

   Continuity should exist. 

   Refer to WIRING DIAGRAM .

3. Check harness continuity between the following terminals and ground.
   Fig 2: Checking Harness Continuity Between Terminals & Ground

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

   Continuity should not exist. 

   Refer to WIRING DIAGRAM .

4. 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.