Kennewick, WA Noise Ordinances: Vehicle Noise (2026)

Vehicle noise in Kennewick is regulated under three overlapping layers. First, WAC Chapter 173-62 (Motor Vehicle Noise Performance Standards) sets in-use dBA limits measured at a 50-foot reference distance: 72 dBA for autos and light trucks (under 10,000 lbs GVWR) at 45 mph or less and 78 dBA at higher speeds; 78 dBA for motorcycles at 45 mph or less and 82 dBA at higher speeds; 86 dBA for heavy vehicles (over 10,000 lbs GVWR) at 35 mph or less. Second, RCW 46.37.390 requires every motor vehicle to be equipped with a muffler in good working order and in constant operation to prevent excessive or unusual noise; muffler cut-outs, bypasses, and exhaust modifications that amplify engine noise are barred on public highways. Vehicles 25 years or older are exempt from the modification prohibition, and competition vehicles in organized sanctioned events are also exempt. Third, the Kennewick Municipal Code's public-disturbance noise provisions reach amplified sound from a vehicle stereo plainly audible at 50 feet on a public street, a standard that is content-neutral under Reed v. Town of Gilbert (2015), 576 U.S. 155. Engine braking on Highway 395 and I-82 corridors is a recurring issue that the Washington State Patrol and Kennewick Police enforce.