Problem: The vehicle would not pass a state smog inspection.
Details: The reason the vehicle would not pass the smog inspection was because the oxygen sensor monitor would not run. There were no diagnostic trouble codes (DTCs). The technician found an OEM-specific drive cycle in ALLDATA Repair. After completing the drive cycle twice, the oxygen sensor monitor still would not run.
Later, a phone call from the customer shed some light on a possible cause. He had replaced the oxygen sensors before the smog inspection with some that he had bought online.
Confirmed Repair: The tech installed new factory oxygen sensors and performed another drive cycle. The oxygen sensor monitor ran as designed and the vehicle passed the smog inspection.