Understanding Smog Check Requirements in California: A County-by-County Guide

California is renowned for its commitment to reducing air pollution and maintaining environmental health. One significant initiative contributing to cleaner air is the state's smog check program, which ensures that vehicles meet emissions standards. However, smog check requirements are not uniform across all counties. For many vehicle owners, understanding the differences between a regular smog check, a STAR smog check, and county-specific exemptions is crucial for staying compliant.

In this guide, we'll break down which counties mandate smog checks, the exceptions, and other key details every vehicle owner needs to know.

Smog Check Requirements: The Big Picture

The California Bureau of Automotive Repair (BAR) oversees the Smog Check Program, which divides the state into three areas based on air quality:

Enhanced Areas: These are highly populated regions with significant air pollution, such as Los Angeles and Sacramento. Vehicles here are subject to more stringent testing.

Basic Areas: These regions have cleaner air but still require smog checks.

Change of Ownership Areas: These are rural areas with the cleanest air. Smog checks are not required for biennial registration renewal but are mandatory when a vehicle is sold or registered for the first time in the state.

Counties Requiring Smog Checks in California

While most counties in California require biennial (every two years) smog inspections as part of vehicle registration, there are some important exceptions. The easiest way to determine if your car needs a smog check is by checking your DMV registration renewal notice, which will clearly state the requirement.

The following counties are generally considered "full biennial" counties where smog checks are a regular part of registration renewal for most vehicles:

Alameda

Butte

Colusa

Contra Costa

Fresno

Glenn

Kern

Kings

Los Angeles (with one key zip code exemption, see below)

Madera

Marin

Merced

Monterey

Napa

Nevada

Orange

Sacramento

San Benito

San Francisco

San Joaquin

San Luis Obispo

San Mateo

Santa Barbara

Santa Clara

Santa Cruz

Shasta

Solano

Stanislaus

Sutter

Tehama

Tulare

Ventura

Yolo

Yuba

The "Partial Biennial" Counties

Six counties have partial smog check requirements based on specific ZIP codes. In these areas, only certain ZIP codes are subject to the biennial smog check for registration renewal. The rest of the county only requires a smog check when a vehicle changes ownership.

These counties are:

El Dorado

Placer

Riverside

San Bernardino

San Diego

Sonoma

For residents in these counties, it is essential to check the official California DMV or BAR websites to verify if their specific ZIP code requires a biennial inspection.

The Single County with a Unique Exemption

In Los Angeles County, the ZIP code 90704 (Avalon or Catalina Island) is exempt from all smog check requirements. This is the only exempted ZIP code in a county that is otherwise fully subject to smog checks.

Key Exemptions from Smog Inspections

It’s important to know that not all vehicles are required to undergo a smog check, even in counties where they are mandatory. The following vehicles are generally exempt:

Newer Vehicles: Gasoline-powered vehicles that are eight model years old or newer are exempt from biennial smog checks. Instead, their owners pay an annual smog abatement fee.

Older Gasoline Vehicles: Vehicles manufactured in 1975 or earlier are exempt.

Diesel Vehicles: Diesel-powered vehicles from 1997 or earlier or with a Gross Vehicle Weight Rating (GVWR) over 14,000 lbs are exempt.

Electric Vehicles (EVs): Since they produce zero tailpipe emissions, all-electric vehicles are exempt.

Natural Gas Vehicles: Natural gas-powered vehicles with a GVWR of more than 14,000 lbs are exempt.

Motorcycles: Motorcycles are not part of the smog check program.

Why Smog Checks Are So Important

Smog checks are designed to identify vehicles with excessive emissions, helping to reduce pollutants like carbon monoxide, nitrogen oxides, and hydrocarbons. These pollutants contribute to smog formation, which poses significant health risks and environmental hazards. By ensuring vehicles meet emission standards, California can maintain cleaner air and protect public health.

How to Check If Your Vehicle Requires a Smog Check

The easiest way to confirm your vehicle's requirement is by checking your DMV registration renewal notice. The notice will clearly indicate if a smog inspection is required and whether it must be a STAR-certified smog check.

For the most up-to-date information on ZIP code requirements or other regulations, the California Bureau of Automotive Repair (BAR) website is the official and most reliable source.

By staying informed and ensuring compliance, Californians can contribute to a cleaner, healthier environment for everyone.