Monterey, CA Noise Ordinances: Vehicle Noise (2026)

For vehicles operating on public roads in unincorporated Monterey County, the governing law is the California Vehicle Code rather than Chapter 10.60. California Vehicle Code Section 27150 requires every motor vehicle to have an adequate muffler in good working order to prevent excessive or unusual noise, and Section 27151 prohibits modifying an exhaust system to amplify or increase noise; Vehicle Code Section 23130 sets statewide vehicle noise limits. These are enforced by the Monterey County Sheriff and the California Highway Patrol. Where a vehicle, generator, refrigeration unit, or off-road machine is operated off the roadway (for example, on private property or at an event), it can also be treated as a noise-producing device under Sec. 10.60.030 of the County Code, which prohibits operating any machine, mechanism, device, or contrivance above the code's daytime cap measured 50 feet away, and during the nighttime period it is subject to the Sec. 10.60.040 'loud and unreasonable sound' prohibition and the 45 Leq / 65 dBA Table 1 standards. Aircraft are expressly excluded from Sec. 10.60.030.