Marin County, CA Noise from Specific Sources: Car Alarm Limits (2026)
Key Facts
- Governing section
- § 6.70.030(1), Marin County Code
- Allowed horn use
- Only as a danger warning
- Prohibited
- Unreasonably loud/harsh sound or duration
- Dedicated car-alarm law
- None; covered under horn/signaling rule
- Penalty
- Misdemeanor, up to $500 or 6 months
Summary
Marin County Code § 6.70.030(1) makes it unlawful to sound a car horn or other vehicle signaling device except as a danger warning, to make it produce an unreasonably loud or harsh sound, or to let it sound for an unnecessary and unreasonable period of time. The county has no separate car-alarm statute; a malfunctioning or prolonged alarm is enforced under this same horn-and-signaling-device provision.
(1)Horns, signaling devices, etc. The sounding of any horn or signaling device on any automobile, motorcycle or other vehicle on any road or public place, except as a danger warning; the creation by means of any such signaling device of any unreasonably loud or harsh sound; and the sounding of any such device for an unnecessary and unreasonable period of time;
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Municipal Code: Supplement 2026 Update 1).
Full Breakdown
70's enumerated-noises section treats vehicle horns and "signaling devices" as its own category before it ever reaches radios, loudspeakers, or construction equipment. " Marin's code does not contain a chapter written specifically for anti-theft car alarms; a vehicle alarm that keeps blaring after a false trigger, or one calibrated to an unreasonably harsh tone, falls within this same signaling-device language because an alarm is, functionally, a signaling device mounted on the vehicle. 270, a misdemeanor punishable by up to a $500 fine, up to six months in county jail, or both.
020's broader ban also reaches any horn or alarm noise that "annoys, disturbs, injures or endangers the comfort, repose, health or peace of others," giving deputies a second hook even outside the specific horn subsection. The Marin County Sheriff's Office handles complaints in the unincorporated area; because the ordinance requires only an unreasonable-duration or unreasonably-harsh-sound showing rather than a decibel reading, an officer can act on witness reports of a car alarm running for an extended period without special equipment.
Violations & Fines
A vehicle horn or alarm violation under § 6.70.030(1) is a misdemeanor by default of the county's general penalty section, § 1.04.270: up to a $500 fine, up to six months in jail, or both, since the subsection is not declared an infraction. Deputies can cite based on an unreasonably harsh tone or an unreasonable duration alone, without a calibrated sound-level test.
Frequently Asked Questions
Does Marin County have a specific car alarm ordinance?
When is it legal to sound a car horn under this rule?
What's the penalty for a horn or alarm noise violation?
Who enforces vehicle noise complaints in unincorporated Marin?
Sources & Official References
Other rules in Marin County
California rules heatmap·Compare Marin County to another location·View the California noise from specific sources overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.