Cold Air Intakes Performance Boost or Eco Risk

Have you ever dreamed of pressing the accelerator and hearing your car roar to life with newfound power? Installing a cold air intake (CAI) system seems like a quick way to make that dream a reality. This relatively simple modification delivers immediate results and is often considered an "entry-level" performance upgrade. But before you reach for your wallet, there's one critical question you need to answer: Is it legal?

Imagine your car's engine as a powerful respiratory system, constantly needing air (more specifically, oxygen) to burn fuel and generate power. The factory intake system functions like a masked respirator—it filters impurities, prevents water ingestion, and reduces noise, but at the cost of restricting airflow.

A cold air intake system removes these limitations. By replacing most of the factory intake components with larger, smoother piping and high-flow air filters, it allows the engine to " breathe" more efficiently. More importantly, these systems typically relocate the air filter away from the engine's heat, sometimes exposing it directly to outside air. This results in cooler, denser air entering the combustion chamber, which can improve power output and fuel efficiency.

However, this modification affects combustion dynamics and air-fuel ratios, potentially interfering with emissions control systems. This brings us to the crucial question: Is it legal to install one?

The legality of cold air intake modifications largely depends on where you live. Some states have no restrictions, while others enforce strict regulations—primarily influenced by standards set by the California Air Resources Board (CARB).

CARB has established emissions regulations for vehicle modifications, including intake systems, that exceed federal requirements. If a cold air intake lacks a CARB Executive Order (EO) exemption, installing it in states that follow CARB standards may be illegal.

As of this writing, the following states and regions adhere to CARB regulations:

• Arizona
• California
• Connecticut
• District of Columbia
• Maine
• Maryland
• Massachusetts
• New Jersey
• New Mexico
• New York
• Oregon
• Pennsylvania
• Rhode Island
• Vermont
• Washington

The good news is that many aftermarket performance intake systems have received CARB EO exemptions, typically indicated by an "EO Number" (e.g., "D-XXX-XX"). This means these systems can be legally installed and used in CARB-compliant states.

In simpler terms, if your cold air intake system carries a CARB EO exemption, you can install it legally even in CARB-regulated states.

Better yet, CARB-approved systems often include prominent labels displaying the EO number. These are affixed to the intake itself, and some manufacturers provide additional decals for visible placement on the vehicle—helpful during emissions testing or inspections.

Manufacturers proudly advertise CARB EO exemptions as a key selling point. Retailers like Summit Racing explicitly list CARB certification as a filterable attribute for intake systems. If no EO number is visible, the system likely isn't legal for use in CARB states.

For absolute certainty, check the manufacturer's official website. If a system is CARB-approved, the information will be readily available.

If you've purchased a used vehicle with an aftermarket intake, how can you verify its legality? Start by locating the part number and cross-referencing it with manufacturer records. If the vehicle previously passed emissions testing in a CARB state, look for EO decals in the engine bay, glove compartment, or fuel door.

If documentation is missing, consider replacing the system with a CARB-certified unit to avoid inspection complications. Note that universal intake kits—common in custom builds—lack CARB approval because they aren't designed for specific vehicle applications.