California Engine Swap Smog Laws

Engine changes are regulated in California.
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The California Department of Consumer Affairs Bureau of Automotive Repair (BAR) maintains strict rules regarding engine replacement or change. In addition to regulating engine changes, certification and inspection will be required by BAR prior to any vehicle with an engine change being allowed to legally operate on California roads.

Engine Change Issues

Due to the stringent equipment and testing standards, the California BAR recommends a vehicle's engine be rebuilt. Where an engine swap is performed, mixing and matching of components is not allowed, even among variants of the same engine in a manufacturer's line.

Certification Issues

An engine-swapped vehicle will require a comprehensive inspection by a BAR official at a BAR referee station. The vehicle must also have a BAR vehicle identification label attached to the doorpost. In addition to the comprehensive inspection, a swapped vehicle will be required to undergo a smog check which consists of three parts: a visual inspection, a functional inspection and a tailpipe emissions test. Note: Light duty smog vehicles do not require smog testing in California.

Smog Issues

Section 3362.1 of the California Code of Regulations forbids any reduction or degradation of a vehicle's emission control system. Any installed engine must maintain all original emission control equipment. The emission equipment must be for the vehicle's model year or newer. Thus swapping an older engine into a new car will not result in the emission standards of the engine applying, the old engine will have to comply with the vehicle model year's standards.