Motor Vehicle Fuels Inspections

This page last reviewed July 2, 2015

Fuels Inspection

A primary component of the ARB's Motor Vehicle Fuels Enforcement program is the inspection of California gasoline and diesel fuel at production, transport, and dispensing facilities.

ARB Fuels Inspectors conduct frequent, unannounced inspections of refineries, service stations, distribution and storage, bulk purchaser and consumer facilities throughout the State of California to obtain samples of gasoline and diesel fuel. The samples are then analyzed in the Mobile Fuels Laboratory.

Mobile Fuels Laboratory

The Mobile Fuels Laboratory is a fully-equipped and self-contained vehicle located in the vicinity of the inspection. The Lab contains instrumentation and support equipment necessary for the immediate testing of gasoline and diesel fuel. For more information, please visit our Mobile Fuels Laboratory web page.

Fuels Analysis

Tests are conducted on fuels samples for compliance with Phase 3 California Reformulated Gasoline (CaRFG) and diesel fuel regulations.

Gasoline (CaRFG) Reid vapor pressure, T50 and T90 distillation temperatures, total aromatics, olefins, and oxygen, benzene, and sulfur contents.
Diesel Fuel Sulfur, aromatic hydrocarbon content, and polynuclear aromatic hydrocarbon content.
Alternative Diesel Fuel Formulations Sulfur, aromatic hydrocarbon content, polynuclear aromatic hydrocarbon content, nitrogen, cetane number, and additives.

Specification and Test Methods for California Gasoline, Motor Ethanol, and Diesel Fuel

The following documents offer a brief and informal summary of specifications and test methods:

Gasoline Specifications
and Test Methods

Motor Ethanol Standards
and Test Methods

Diesel Fuel Specifications
and Test Methods

What Happens When a Violation is Discovered?

After violations are documented by inspectors, further investigation is conducted. ARB staff evaluate the data, determine the cause and severity of the violation, and prepare the case. Most cases are resolved through ARB's mutual settlement program or referred for settlement or litigation. For more information about fuels case development, please contact Mark Stover, Manager of the Fuels Enforcement Section, at (916) 229-0757.


For further information about fuels inspections, please email Frederick Schmidt or telephone (916) 229-0399. For contact information regarding other ARB Enforcement programs, please visit our Enforcement Contacts web page.