Daly City, CA Noise Ordinances: Vehicle Noise (2026)

California Vehicle Code § 27150 requires every motor vehicle to be equipped with an adequate muffler in constant operation to prevent excessive or unusual noise, and § 27151 prohibits modification that amplifies exhaust noise above stock. Cal. Veh. Code § 27201 sets the maximum sound level for passenger cars and light trucks at 80 dB(A) measured at 50 feet under specified test conditions; § 27202 sets 86 dB(A) for motor trucks over 6,000 lbs; § 27203 sets 82 dB(A) for motorcycles. Cal. Veh. Code § 23130 prohibits operating any vehicle that exceeds these noise limits on a highway. Cities are preempted from imposing different noise standards on vehicles in motion on public roads (Veh. Code § 21 preemption doctrine; see also Caltrans noise enforcement guidance). However, Daly City retains authority over (1) stationary vehicles on private property under Chapter 9.22, (2) car alarms and audio systems audible across property lines (§ 9.22.030 nighttime rule), and (3) modified-exhaust 'side show' or street-racing activity which may also trigger Cal. Veh. Code § 23109 (exhibition of speed).