Mendocino County, CA Noise Ordinances: Vehicle Noise (2026)

Noise from cars, trucks and motorcycles on public roads is regulated by the California Vehicle Code, which applies statewide and is enforced by the Mendocino County Sheriff and the California Highway Patrol. Vehicle Code Section 27150(a) requires every motor vehicle to be equipped with an adequate muffler in constant operation and properly maintained to prevent excessive or unusual noise, and prohibits exhaust cutouts and bypasses. Vehicle Code Section 27151(a) makes it illegal to modify an exhaust system so that it amplifies or increases noise beyond the limits set for that type of vehicle; for passenger vehicles under 6,000 pounds gross vehicle weight (other than motorcycles), an exhaust producing 95 dBA or less under the applicable SAE test standard complies. The county's general Chapter 8.100 noise ordinance can also reach loud machinery and vehicles on private property during nighttime quiet hours (10:00 p.m. to 7:00 a.m.), but on-road vehicle noise itself is principally a Vehicle Code matter. Idling, off-road and stationary equipment may additionally be subject to state air-resources rules.