Boston, MA Noise from Specific Sources: Car Alarm Limits (2026)
Key Facts
- Audibility trigger
- Plainly audible at 200 feet
- Auto-shutoff requirement
- Must stop within 5 minutes
- Fine
- $50 per violation
- Enforcement track
- Noncriminal disposition, M.G.L. c. 40 § 21D
- Code placement
- Boston Environment Protection Ordinances
Summary
Boston bans car alarms and anti-theft devices that make noise audible from 200 feet away and do not shut themselves off within five minutes. Violating the rule draws a flat $50 fine, enforced under the city's Environment Protection Ordinances alongside the state noncriminal disposition process.
The use, maintenance, installation or keeping of any device whose purpose it is to protect an owner's vehicle from damage and/or theft through the mechanical creation of a noise of sufficient magnitude to be plainly audible at a distance of 200 feet from such device which does not automatically terminate any such noise within five minutes shall be unlawful. Penalty for violation of this Section shall be a fine of $50. This Section shall be deemed a part of the Environment Protection Ordinances, so called, and shall be enforced pursuant to the provisions of M.G.L. Chapter 40, Section 21D.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-2: Current through Ordinance 2025 C. 14, passed 11-5-2025).
Full Breakdown
2 makes it unlawful to use, maintain, install or keep any vehicle anti-theft or protective device that mechanically creates a noise loud enough to be plainly audible at a distance of 200 feet from the device, unless the device automatically shuts off within five minutes of triggering. 3, restates the same 200-foot, five-minute standard as a prohibition on the 'use' of such a device and carries the identical $50 fine; both sections trace to companion 1984 ordinance chapters (Ord. 1984 c. 4 and c. 5) folded into the 1985 Code recodification.
L. Chapter 40, Section 21D, meaning violations are typically resolved by ticket rather than criminal prosecution. The alarm rule sits in the same Chapter XVI, Article on Noise Control as Boston's general 50/70 dBa day-night noise standard, its construction-hours curfew and its residential loud-amplification-device bans, all of which are separately enforceable and can apply on top of the alarm-specific fine if a triggered alarm also exceeds the general noise threshold. Because the standard is device-based (audibility distance and shutoff time) rather than a straight decibel reading, Police or an Environment Department designee can cite a violation without needing a calibrated sound meter reading, unlike the general noise provisions that require dBa measurement.
Violations & Fines
Using, installing, maintaining or keeping a car alarm that is audible at 200 feet and fails to self-terminate within five minutes is unlawful and punishable by a fine of $50 under § 16-26.2 (and the parallel § 16-26.3). Fines are processed through the noncriminal disposition procedure under M.G.L. Chapter 40, Section 21D rather than as a criminal charge.
Frequently Asked Questions
Is it illegal to have a loud car alarm in Boston?
What is the fine for a Boston car alarm violation?
Does the car alarm rule apply everywhere in the city?
Sources & Official References
Other rules in Boston
Compare Boston to another location·View the Massachusetts noise from specific sources overview
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