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

Within Chapter 13 of the Colusa County Code (Ord. No. 730), Section 13-9 specifically addresses vehicle repair noise: it is unlawful for any person within any residentially zoned or residentially planned-development zoned area of the county to repair, rebuild, or test any motor vehicle in a manner that exceeds the limits set for residential zones in Table No. 1, measured at the property plane. Those residential limits are 50 dBA between 9 p.m. and 7 a.m. and 55 dBA between 7 a.m. and 9 p.m. The county's definition of 'sound amplifying equipment' in Section 13-2 expressly excludes vehicle radios, CDs, and tape players when heard only by the vehicle's own occupants, and excludes lawful emergency-vehicle and traffic-safety warning devices. On public streets and highways, vehicle exhaust and engine noise is governed by California state law rather than the county code: Vehicle Code Section 27150 requires every motor vehicle to have an adequate muffler in constant operation to prevent excessive or unusual noise and bars exhaust cutouts or bypasses, and Section 27151 prohibits modifying an exhaust system to amplify or increase vehicle noise beyond the limits set for the vehicle type. These rules apply throughout unincorporated Colusa County.