What is required for vehicles that have aftermarket catalytic converters to pass a smog check?

For vehicles equipped with aftermarket catalytic converters to pass a smog check, it is essential that there is documentation proving compliance with emission standards. This documentation serves as evidence that the aftermarket component meets the specific emissions regulations set by the state or federal authorities.

Proper documentation typically includes details such as the converter's make and model, certification by an emissions compliance body, or information confirming that it adheres to the necessary performance and emissions standards. The presence of this documentation provides inspectors with the assurance that the aftermarket part will not contribute to excessive emissions and conforms to the legal requirements for the vehicle category.

In contrast, while labeling by the manufacturer and installation by a licensed technician are beneficial practices for ensuring that an aftermarket catalytic converter is of good quality and properly fitted, they do not by themselves guarantee compliance with emission standards. Additionally, the requirement to remove all aftermarket parts for testing would not be applicable since it would prevent the assessment of how well the aftermarket converter performs under real-world conditions. Therefore, proper documentation is the critical factor that enables the smog check to validate the converter’s legality and functionality.