ATCM 93120 Phase 2 is a smog-control requirement that affects which vehicles can register in California, depending on their model year and emissions equipment

ATCM 93120 Phase 2 refers to an Air Resources Board rule that sets emissions standards for aftermarket catalytic converters and related parts installed on vehicles. If you are registering a vehicle in California or renewing registration for one you already own, this rule determines whether certain replacement parts meet state requirements. Vehicles that fail to meet Phase 2 standards cannot pass the smog check required for registration in most California counties.

The rule applies primarily to vehicles model year 2009 and newer. If you have recently had catalytic converter work done, or if you are buying a used vehicle that has had aftermarket emissions equipment installed, you need to know whether those parts comply with Phase 2 standards. Non-compliant parts will cause your vehicle to fail smog inspection, which blocks registration renewal.

Key Takeaways

  • ATCM 93120 Phase 2 sets emissions standards for aftermarket catalytic converters and oxygen sensors on vehicles model year 2009 and newer in California.
  • Your vehicle must pass a smog check showing compliance with Phase 2 standards before you can renew registration in most California counties.
  • If your vehicle has had aftermarket emissions parts installed, those parts must carry CARB certification numbers to be legal in California.
  • You can check whether a part is Phase 2 compliant by looking for the CARB Executive Order number on the part itself or on the installer's paperwork.
  • If your vehicle fails smog inspection due to non-compliant parts, you will need to replace them with certified parts before registration can proceed.

Which vehicles are affected by Phase 2 requirements

ATCM 93120 Phase 2 applies to light-duty vehicles (cars, SUVs, and light trucks) with model years 2009 and newer. If your vehicle is older than 2009, it may be subject to different emissions rules or may not require a smog check at all, depending on your county and the vehicle's age.

The rule covers any vehicle that has had a catalytic converter, oxygen sensor, or other emissions control part replaced with an aftermarket component. If your vehicle still has its original manufacturer equipment, Phase 2 does not directly affect you — your vehicle will pass smog inspection based on its original design. However, if you plan to have emissions work done before registration renewal, the replacement parts must meet Phase 2 standards.

What Phase 2 compliance means for smog inspection

When you take your vehicle for a smog check, the technician will test whether your vehicle's emissions fall within legal limits. If your vehicle has aftermarket emissions parts that do not meet Phase 2 standards, it will fail this test. The smog check report will note that the vehicle has non-compliant equipment.

Once a vehicle fails smog inspection due to non-compliant parts, you cannot renew registration until those parts are replaced with Phase 2-certified equipment. The California Department of Motor Vehicles will not process your registration renewal without a passing smog report. This means you need to identify which part is non-compliant, have it replaced, and then schedule a new smog inspection before you can complete registration.

How to verify if aftermarket parts meet Phase 2 standards

Aftermarket emissions parts that meet Phase 2 standards carry a CARB Executive Order number printed on the part itself. This number looks like "Executive Order D-XXX-XXX" or similar. If you have paperwork from a recent repair or replacement, the invoice should list this Executive Order number. You can also search the California Air Resources Board website for the specific part number to confirm it has been certified.

If you are buying a used vehicle and the seller tells you it has had emissions work done, ask to see the original repair invoice. That invoice should show the CARB Executive Order number for any parts that were installed. If the seller cannot provide documentation, you can have a smog technician inspect the vehicle before you buy it to determine whether the parts are compliant.

If you are planning to have emissions work done before registration renewal, ask the repair shop whether the parts they plan to use are Phase 2 certified. A reputable shop will have this information readily available and should provide you with documentation showing the CARB Executive Order number once the work is complete.

What happens if your vehicle fails smog inspection

If your vehicle fails smog inspection because of non-compliant aftermarket parts, the smog report will identify the problem. You will need to take your vehicle to a repair shop and have the non-compliant part replaced with one that carries CARB certification. This is a required step — you cannot register your vehicle without a passing smog report.

The cost of replacement parts varies depending on which component is non-compliant and which certified part you choose. Catalytic converters, for example, range widely in price depending on the vehicle and the manufacturer. Once the part is replaced, you will need to schedule a new smog inspection. Some smog stations offer a retest fee that is lower than the initial inspection fee, though this varies by location.

After you receive a passing smog report, you can proceed with your registration renewal through the DMV. You will need to submit the passing smog report along with your registration renewal process.

Phase 2 requirements for different vehicle types

ATCM 93120 Phase 2 standards explore differently depending on what type of emissions equipment is being replaced. Catalytic converters must meet specific efficiency and durability standards. Oxygen sensors must be compatible with the vehicle's onboard diagnostic system. Some vehicles may have other emissions components that are subject to Phase 2 certification.

If your vehicle is a hybrid or electric vehicle, different rules may explore. Some hybrid vehicles have catalytic converters, while others do not. Electric vehicles do not have catalytic converters at all. If you own an electric vehicle, Phase 2 requirements do not explore to your registration, though you may still need to pass other vehicle inspections depending on your county.

Where to find certified parts and repair shops

The California Air Resources Board maintains a list of certified aftermarket emissions parts on its website. You can search by vehicle make, model, and year to find parts that carry CARB Executive Order numbers. This list is updated regularly as new parts are certified.

When choosing a repair shop, ask whether they work with CARB-certified parts and whether they can provide documentation of the Executive Order number once work is complete. Many shops that specialize in emissions work are familiar with Phase 2 requirements and can guide you toward compliant options. If you are having work done at a general repair shop, confirm in advance that they understand Phase 2 standards and will install only certified parts.

Frequently Asked Questions

Do I need to worry about Phase 2 if my vehicle has original equipment?

No. Phase 2 standards explore only to aftermarket parts. If your vehicle still has its original catalytic converter and oxygen sensors, it will pass smog inspection based on its original design. You only need to be concerned about Phase 2 if you have had emissions work done or are planning to have it done.

Can I register my vehicle if it fails smog inspection due to non-compliant parts?

No. The DMV will not process registration renewal without a passing smog report. You must have the non-compliant part replaced with a Phase 2-certified part, pass a new smog inspection, and then submit the passing report with your registration renewal.

Where can I find the CARB Executive Order number for my parts?

The number is printed directly on the part itself. If you have the original repair invoice, it should also list the Executive Order number. You can search the California Air Resources Board website by part number to confirm certification if you are unsure.

What if the repair shop I used did not provide CARB documentation?

Contact the shop and ask for the Executive Order number of the parts they installed. If they cannot provide it, the parts may not be certified. You may need to have them replaced with certified parts before your vehicle can pass smog inspection.

Are there any vehicles exempt from Phase 2 requirements?

Vehicles model year 2008 and older are generally not subject to ATCM 93120 Phase 2. Electric vehicles and some hybrid vehicles may have different requirements. Check with your local smog station or the California Air Resources Board if you are unsure whether your vehicle is affected.