What's a CARB Executive Order, and what does it mean for your vehicle?

What Is a CARB Executive Order and What Does It Mean for Your Vehicle?

Quick answer: A CARB Executive Order (EO) is an exemption the California Air Resources Board grants to an aftermarket part after an engineering evaluation shows the part doesn't increase vehicle emissions. It allows that part to be installed on the specific emission-controlled vehicles the EO covers.

Why EOs exist

Under California Vehicle Code Section 27156(b): "No person shall disconnect, modify, or alter any such required device." Subdivision (c) bars installing, selling, offering for sale or advertising a device for use with, or as part of, a required pollution control system "that alters or modifies the original design or performance of the motor vehicle pollution control device or system."

Subdivision (h) is the exception: the section doesn't apply to a modification or modifying device "found by resolution of the State Air Resources Board" either "(1) Not to reduce the effectiveness of a required motor vehicle pollution control device" or "(2) To result in emissions from the modified or altered vehicle that are at levels that comply with existing state or federal standards" for that model year.

When CARB's evaluation shows a part doesn't increase emissions, CARB grants an exemption from the anti-tampering laws: the Executive Order. Every EO part has an assigned number that Smog Check stations, BAR Referee stations and CARB can look up.

Which parts usually need one

BAR's Smog Check Manual uses CARB's definitions to sort aftermarket parts:

• Add-on parts (examples given: superchargers, turbochargers, nitrous oxide kits) generally need an EO.
• Modified parts (examples given: performance camshafts, performance cylinder heads, performance engine management components) generally need an EO.
• Replacement parts that are functionally identical to the original, like replacement air filter elements and spark plugs, don't.
• Consolidated parts, which replace a group of original parts and work identically, don't.

CARB's enforcement advisory names exhaust headers, software tuners, air intakes, superchargers and turbochargers as performance parts that typically need an EO.

One name, two kinds of EO

CARB also issues Executive Orders certifying new vehicles, by engine family or test group, for a specific model year. That's a different document from a part's EO.

An EO also isn't an endorsement. CARB's exemption procedures say manufacturers may not use an EO as an endorsement or approval by CARB.

Practical steps

1. For each emissions-related part, look for an EO number on the label, packaging or paperwork.
2. Read the EO at CARB and read which vehicles it lists.
3. Save a copy of what you find next to your receipt.
4. Questions? CARB's helpline is (800) 242-4450 or helpline@arb.ca.gov.

At a Smog Check, the inspector makes the call; the Smog Check Referee handles disputes.

What Showgone can and can't do here

Showgone keeps each part's receipt, photos and EO number together, with a link to check the EO at CARB. Showgone isn't CARB, BAR, the DMV or a smog station, and a Showgone record isn't an official certificate.

Add this part to your free Showgone garage.

Not legal advice.

Sources

• CARB: Aftermarket, Performance, and Add-on Parts
• CARB: Aftermarket, Performance, and Add-on Parts, About
• California Vehicle Code Section 27156(b), (c) and (h)
• CARB: California Racing Vehicles: Aftermarket Parts & Executive Orders
• CARB Enforcement Advisory #292 (July 10, 2020)
• CARB: Procedures for Exemption of Add-On and Modified Part(s) for On-Road Vehicles/Engines (adopted June 29, 2021), Section IX
• BAR: Smog Check Manual (April 2025), Appendix C definitions
• BAR: Smog Check: When you need one and what's required
• CARB: Aftermarket parts lookup

Date checked: 2026-10-20