Murrieta, CA Noise Ordinances: Vehicle Noise (2026)

Noise from ordinary on-road motor vehicles is largely outside the county's hands. Riverside County's General Plan Noise Element (Policy N 9.1) directs the county to 'enforce all noise sections of the State Motor Vehicle Code' and explains that noise generated by motor vehicles over public roads is preempted from local regulation. Under California law, Vehicle Code section 27150 requires every motor vehicle to have an adequate muffler in constant operation and properly maintained to prevent any excessive or unusual noise, with no cutout or bypass; section 27151 bars modifying an exhaust system to amplify noise, and for vehicles under 6,000 pounds gross weight (other than motorcycles) a sound level of 95 dBA or less under SAE Standard J1169 complies. Vehicle Code section 27007 prohibits operating a vehicle sound amplification system that can be heard outside the vehicle. Where the county does regulate is in Ordinance No. 847, Section 6(a): off-highway vehicles must have a USDA-qualified spark arrester and a constantly operating muffler (no cutout/bypass), and may not emit more than 96 dBA (vehicles made on or after Jan. 1, 1986) or 101 dBA (older vehicles), measured 20 inches from the tailpipe per SAE J-1287. Motor-vehicle sound systems may not be audible inside any inhabited dwelling between 10:00 p.m. and 8:00 a.m., or audible more than 100 feet from the vehicle at other times.