Washington County, OR Noise Ordinances: Vehicle Noise (2026)
Key Facts
- Horn rule
- no non-emergency use, § 8.24.040(A)
- Exhaust brakes
- banned except emergency stops
- Muffler requirement
- effective muffler required, § 8.24.040(E)
- First-offense fine
- up to $500
- Repeat-offense fine
- up to $1,000 within 2 years
- Scope
- unincorporated county only
Summary
Washington County Code § 8.24.040(A), (C) and (E) bar unnecessary horn use, exhaust brakes except for emergency stops, and any vehicle exhaust discharged without an effective muffler. Violations are prima facie noise offenses enforced under the unincorporated-county noise chapter, separate from state vehicle-equipment statutes that also apply.
A.Horns, Signaling Devices, Etc. Sounding of any horn or signaling device on any automobile, motorcycle, or other vehicle on any street or public place in the county, except as a danger warning; the creation by means of any signaling device of any unreasonably loud or harsh sound; and the sounding of any such device for an unnecessary and unreasonable period of time;C.Exhaust Brakes. The use of exhaust brakes except when used for an emergency stop or to slow to avoid a collision;E.Exhausts. The discharge into the open air of the exhaust of any steam engine, stationary internal combustion engine, motor boat, motorcycle, or motor vehicle except through a muffler or other device which will effectively prevent loud or explosive noises therefrom.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Community Development Code: Supplement 2 | Code of Ordinances: Supplement 25).
Full Breakdown
Washington County's noise chapter singles out three vehicle-related acts as prima facie violations. 040(A) bars sounding 'any horn or signaling device on any automobile, motorcycle, or other vehicle on any street or public place in the county, except as a danger warning,' along with any unreasonably loud or harsh signaling sound or sounding a horn for an unreasonable period. Subsection C bars 'the use of exhaust brakes except when used for an emergency stop or to slow to avoid a collision', targeting engine/Jake-brake noise from trucks.
080 sets fines up to $500 for a first conviction and up to $1,000 for a repeat conviction within two years, with each day of continued violation a separate offense. 065. As with the rest of the chapter, these vehicle-noise provisions apply only in unincorporated Washington County, Hillsboro and Beaverton drivers are covered by their own city codes.
Violations & Fines
Sounding a horn other than as a danger warning, using an exhaust/Jake brake outside an emergency stop, or running a vehicle without an effective muffler violates § 8.24.040(A)/(C)/(E). Section 8.24.080 fines reach up to $500 for a first conviction and up to $1,000 for a second conviction within two years, with each day of continued violation a separate offense.
Frequently Asked Questions
Are engine/Jake brakes illegal on Washington County roads?
Is honking a car horn ever allowed at night in the county?
What's the penalty for a loud, unmuffled vehicle exhaust in the county?
Sources & Official References
Other rules in Washington County
Compare Washington County to another location·View the Oregon noise ordinances overview
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