With GST

Start engine and warm it up to the normal operating temperature.
Turn ignition switch OFF and wait at least 10 seconds.
Start engine and keep the engine speed between 3, 500 and 4, 000 rpm for at least 1 minute under no load.
Let engine idle for 1 minute.
Open engine hood.
Set voltmeter probes between ECM terminals ECM terminals 55 [HO2S2 (bank 1) signal], 74 [HO2S2 (bank 2) signal] and ground.
Keep engine speed at 2, 500 rpm constant under no load.
Make sure that the voltage does not vary for more than 5 seconds.

Fig 1: Checking ECM Voltage
Courtesy of NISSAN NORTH AMERICA, INC.

If the voltage fluctuation cycle takes less than 5 seconds, go to "DIAGNOSTIC PROCEDURE ".
- 1 cycle: 0.6 - 1.0 → 0 - 0.3 → 0.6 - 1.0