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FAQs: Colorado’s new aftermarket catalytic converter regulation

Here’s what Colorado installers and parts distributors need to know regarding the regulation effective Jan. 1

Denver—Beginning January 1, 2021, all sales or installation of aftermarket catalytic converters for any model year vehicle must comply with the Air Quality Control Commission, Regulation Number 20, 5 CCR 1001-24. This new regulation prohibits:

• Any person to install, sell, offer for sale, or advertise any Aftermarket Catalytic Converter intended for use on any motor vehicle originally equipped with a catalytic converter(s) in Colorado unless it has been exempted pursuant to the requirements of California Code of Regulations, Title 13, Section 2222 (h) (i.e., a “California Aftermarket Catalytic Converter”).

• Any person to install, sell, offer for sale, or advertise any used, recycled, or salvaged catalytic converter in Colorado pursuant to the requirements of California Code of Regulations, Title 13, Section 2222 (h) and (i).

Q: Under what circumstances would I install an aftermarket catalytic converter?

A: An aftermarket catalytic converter may be installed when the vehicle is beyond its emissions warranty period and the converter has been physically damaged, has a melted or compromised substrate, or is no longer meeting performance standards.

Q: How do I determine if a vehicle is still under its emissions warranty?

A: Installers may reference the vehicle owner’s manual/warranty booklet or contact the vehicle manufacturer or its representative to verify the applicable OEM converter warranty. The vehicle’s odometer reading and age of the vehicle can then be compared to the mileage and age limitations covered under the emissions warranty.

Q: How do I determine if a Colorado-legal aftermarket catalytic converter is available for a vehicle?

A: Installers and sellers should first reference the catalog developed by the aftermarket catalytic converter manufacturer that is specific to Colorado. If a converter cannot be identified in the Colorado specific catalog, installers and sellers should then reference the approved aftermarket catalytic converters at the following website:

http://www.arb.ca.gov/msprog/aftermkt/devices/amquery.php.

These exemptions are issued through Executive Orders. Executive Orders for pre-OBD II and OBD II converters can be sorted by Executive Order number, or by converter manufacturer. Aftermarket catalytic converters sold after January 1, 2009, will also have the California Air Resources Board  Executive Order number permanently labeled on the converter shell.  If you still have questions, please contact the Colorado Department of Public Health and Environment at (888)-861-2646. 

Q: What if a customer arrives with a missing catalytic converter on a vehicle that is still under the emissions warranty. Can I install an aftermarket catalytic converter for this vehicle?

A: No. Because the vehicle and converter are still within the emissions warranty period, an OEM converter is required to be installed. No aftermarket catalytic converters can be legally installed on vehicles that are within their emissions warranty period.

Q: What if none of the manufacturers produce the catalytic converter for the vehicle of interest?

A: This is becoming rare; however, in a scenario that the installer or seller cannot locate an ARB approved converter, the installer or seller should call the Colorado Department of Public Health and Environment (888-861-2646) for additional assistance.

Q: Can an installer adjust the converter installation in cases where the size of the inlet and outlet pipes do not match the exhaust system (for example, by welding in pipe size adaptors)?

A: No. The fact that the pipe sizes do not match is an indication that the catalytic converter part number is not approved for use on the specific vehicle model in question. Therefore, the installation would not be legal.

Q: Can aftermarket catalytic converters exempted under this new regulation be used to replace converters for diesel-powered vehicles?

A: No. Regulations for non-OEM aftermarket catalytic converters apply only to gasoline-powered vehicles. Similar provisions currently do not exist to allow lower performing non-OEM catalytic converters for use on diesel-powered vehicles. Therefore, replacement catalytic converters intended for use on diesel vehicles are required to be functionally identical to the component originally installed by the vehicle or engine manufacturer pursuant to federal regulations.

Q: What is the penalty for installing a non-CARB approved converter?

A: Pursuant to Colorado Revised Statutes 25-7-122(1)(b), Any person who violates Regulation Number 20, 5 CCR 1001-24, can be subject to a civil penalty of not more than fifteen thousand dollars ($15,000) per day for each day of such violation.

Catalytic Converter Type   Legal for Use beginning January 1st, 2021 
New original equipment (OEM) convertersYes. If the vehicle is within the emissions warranty period, a new OEM catalytic converter is required to be installed. If the vehicle is outside of the emissions warranty period, an OEM catalytic converter or an aftermarket catalytic converter that has been exempted (approved) by the California Air Resources Board may be installed.
New aftermarket convertersYes. Aftermarket catalytic converter models sold or installed on or after January 1, 2021 must be exempted under Colorado Regulation 20. Aftermarket converters must be approved by the California Air Resources Board. Approved converters can be confirmed in the catalytic converter manufacturer catalog for Colorado applications, and many applications are listed in the California Air Resources Board aftermarket parts online database.
Certified used OEM convertersNo, used converters may not be sold for use or installed on a vehicle after January 1, 2021.  
Used aftermarket converters or uncertified used OEM convertersNo 

Additional information:

Website: https://cdphe.colorado.gov/aftermarket-catalytic-converters

Phone: (888) 861-2646

Email Contact: CDPHE_mobile@state.co.us

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