Twain Harte, CA Noise Ordinances: Vehicle Noise (2026)

Vehicle noise is one area where the absence of a local Tuolumne County ordinance matters little, because California regulates motor-vehicle noise on public roads statewide and that law applies uniformly in the unincorporated county. Under California Vehicle Code section 27150, every motor vehicle must at all times be equipped with an adequate muffler in constant operation and properly maintained to prevent excessive or unusual noise, and cutouts or bypasses are prohibited. Section 27151 makes it unlawful to modify a vehicle's exhaust so that it amplifies or increases noise beyond the limits allowed by law; for vehicles under 6,000 pounds, the applicable exhaust sound-level standard is 95 decibels. Separately, California Vehicle Code section 27007 bars operating a sound amplification system in a vehicle that can be heard outside it from 50 feet or more when a peace officer asks that it be turned down. Maximum highway noise limits for passing vehicles are addressed in Vehicle Code section 23130. These provisions are enforced by the Tuolumne County Sheriff's Office and the California Highway Patrol. Because the county itself has no noise ordinance, off-road or stationary engine noise on private property is addressed, if at all, through California's general disturbing-the-peace and nuisance laws rather than a local vehicle-noise rule.