California Law on Cold Air Intakes

Most stock air intakes draw air from inside the engine bay, where air temperatures run extremely hot. Cold air intakes often draw air from outside the engine bay, where air temperatures are cooler. Colder air is denser air, meaning it carries more oxygen, and the more air that can be crammed into an engine, the bigger the "bang" it can create, resulting in more power.

The California Air Resources Board (CARB) is a governing body designed to research and create ways to eliminate air pollution. CARB states on its website that its mission is "to promote and protect public health, welfare and ecological resources through the effective and efficient reduction of air pollutants."

CARB seeks to reduce air pollution by enacting laws that limit the amount of pollutants and harmful gases a car may emit. A new vehicle must meet or exceed the standards established by CARB in order to be legally sold and registered in California. To achieve these standards, vehicles require a complex array emissions control systems to keep pollutants at or under the legal CARB-approved limits.

Modifying or tampering with a vehicle's engine can reduce the functionality of its emission controls. As such, California and CARB have established an anti-tampering law, Vehicle Code Section 27156 (VC 27156). The act of adding any aftermarket part, including a cold air intake, is considered an act of tampering with a smog-controlled engine. In other words, you could be breaking California law by adding an aftermarket cold air intake onto their vehicle, unless that cold air intake has received a CARB-issued exemption.

Getting an aftermarket engine part to meet CARB certification is a costly and lengthy process. An aftermarket product that has been CARB-certified has been thoroughly evaluated and tested to prove that it is reliable and won't increase a vehicle's harmful emissions. CARB-certified aftermarket products will have a sticker or badge with a number detailing its Executive Order (EO) exemption status. This EO number will show smog control technicians, members of law enforcement and others that the part does not violate VC 27156.

In order to pass California's smog check requirement, engines must pass both a visual inspection and a "sniffer" (emissions measuring) test before it is allowed to legally drive on public roads. A cold air intake without a CARB-approved EO number will not pass a visual smog inspection. This means that the car will not be legally allowed to drive on the road until the intake has been replaced with a CARB-approved part, even if the sniffer test is clean. Law enforcement officers can also issue citations should they determine and confirm that a vehicle is running without a CARB-approved cold air intake.