Aftermarket Catalytic Converters

In order to be sold and installed in the state, aftermarket catalytic converters must be exempted from California’s anti-tampering laws.  If an aftermarket catalytic converter is shown to be durable and meets vehicle emission control requirements, it is granted an exemption Executive Order (EO) that allows it to be installed on specific emission controlled vehicles.

Aftermarket Catalytic Converter Requirements

1995 and Older Vehicles (Pre OBD II)

On non-OBD II vehicles, smog inspectors are required to ensure that all aftermarket catalytic converters installed on the vehicle have an EO number that covers vehicles within the correct vehicle category (PC-1, PC-2, T-1, or T-2). Refer to the ARB Web site for a separate Pre-OBDII EO Listing containing the EO numbers and corresponding vehicle categories.

Inspectors are not required to check specific vehicle application using the series or part numbers on non-OBD II vehicles.

Most 1996 and Newer Vehicles (OBD II)

Emissions control information labelIn order to comply with California’s anti-tampering laws, and pass the smog inspection, the part numbers on aftermarket catalytic converters that are installed on OBD II vehicles must be approved for the vehicle’s make, model, model year, engine size and test group/engine family designation.

To verify application, inspectors must verify the EO and part number against the ARB Aftermarket Catalytic Converter Database. Each EO contains a catalog listing the applicable vehicles.

Unlike non-OBD II vehicles, it is important to note that inspectors are required to check specific vehicle application using the series and part number.

For more information about add-on and modified parts, or aftermarket catalytic converters, please contact ARB’s Public Information Helpline at (800) 242-4450.

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