3. Check HO2S2 Heater Output Signal Circuit For Open And Short

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

Turn ignition switch OFF.
Disconnect ECM harness connector.
Check harness continuity between ECM terminal and HO2S2 terminal as follows.
Refer to WIRING DIAGRAM.

Fig 1: Check HO2S2 Heater Output Signal Circuit For Open And Short
Courtesy of NISSAN MOTOR CO., U.S.A.
1. 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.