D6: Check For O2 Sensor Failure

With the conditions held as in D5, run the engine at 1500 rpm for approximately 3 minutes.

Does the displayed voltage drop below 400mV and rise above 500mV, cycling approximately every 180 seconds?

Yes
GO to D8, D8: Check For O2 Sensor Continuity

No
Renew O2 sensor. Reconnect plug(s).
GO to D7, D7: Stop