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

WARNING: This page is about a different car, the 2004 Infiniti G35. However, it is still accessible from the selected car via links, so may be relevant.

Turn ignition switch OFF.
Disconnect corresponding heated oxygen sensor 1 (HO2S1) harness connector.
Disconnect ECM harness connector.
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.
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.
Check harness continuity between HO2S1 terminal 4 and ECM terminal 78.
Continuity should exist.
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.