How does a smog check inspector confirm the functionality of a vehicle’s catalytic converter?

A smog check inspector confirms the functionality of a vehicle’s catalytic converter primarily by ensuring that the On-Board Diagnostics (OBD) system is functioning correctly and does not indicate any faults. This system monitors the vehicle's emissions control components, including the catalytic converter, and will alert the driver or inspector to any malfunctions through diagnostic trouble codes (DTCs). If the OBD system shows no faults, it suggests that the catalytic converter and other related components are likely operating as intended.

In addition to checking the OBD system, the inspector may also perform a visual inspection of the catalytic converter to look for signs of damage or tampering, but the primary confirmation comes from the data provided by the OBD. Simply replacing the catalytic converter before testing, conducting a visual inspection for damage alone, or checking engine oil levels do not provide adequate confirmation of the catalytic converter's functionality in terms of its ability to reduce emissions effectively.