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Los Angeles County, CA Noise from Specific Sources: Car Alarm Limits (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified August 2026

Key Facts

Auto-silence deadline: 15 minutes after activation
Routine alarm test window: 7:00 a.m.–7:00 p.m., max 60 sec
Full-system test allowed: Once per month, 7 a.m.–10 p.m.
Enforcing officer: County Health Officer
Penalty: Up to $500 fine, 6 months jail

Summary

Unincorporated Los Angeles County requires any sounding motor-vehicle burglar alarm to shut off within 15 minutes of activation, treating a longer-running alarm itself as a noise-code violation regardless of decibel level.

City-specific rules exist: El Monte, Glendale, Santa Monica, Long Beach, Los Angeles, and Downey have their own car alarm limits rules that differ from Los Angeles County's county-level regulations. If you live in one of those cities, check the city-specific page instead.

Sounding or permitting the sounding of any exterior burglar or fire alarm, or any motor-vehicle burglar alarm is prohibited, unless such alarm is terminated within 15 minutes of activation.

Source: LA County Code Ch. 12.08 – Noise ControlView official code

Full Breakdown

A). 1-2). 08 noise-control scheme that covers exterior noise standards. There is no exemption listed for car alarms beyond the 15-minute limit itself; an alarm owner whose system re-triggers or fails to auto-silence is in violation from the 16th minute onward.

Violations & Fines

Sounding a motor-vehicle or building burglar/fire alarm past the 15-minute mark violates § 12.08.500.C and is a misdemeanor under § 12.08.670, carrying a fine of up to $500, up to six months in County Jail, or both. Each day the violating condition is permitted to continue is charged as a separate offense; the health officer typically issues a written correction notice first under § 12.08.660.

Frequently Asked Questions

How long can a car alarm legally sound in unincorporated LA County?

No more than 15 minutes from activation. County Code § 12.08.500.C prohibits sounding any motor-vehicle burglar alarm "unless such alarm is terminated within 15 minutes of activation," regardless of how loud it is.

Can I test my car or home alarm whenever I want?

No. Routine testing of a stationary emergency signaling device is limited to 7:00 a.m.-7:00 p.m. with a maximum 60-second cycle, and a full system test is allowed only once per calendar month between 7:00 a.m. and 10:00 p.m., per § 12.08.500.B.

Who enforces the 15-minute alarm rule?

The county health officer, who administers all of Chapter 12.08's noise regulations, including making measurements and issuing written correction notices before any citation under § 12.08.660.

What's the penalty for an alarm that won't stop?

A violation of § 12.08.500 is a misdemeanor under § 12.08.670: up to a $500 fine, up to six months in County Jail, or both, with every day the condition continues counted as a separate offense.

Sources & Official References

[1]Los Angeles County Code, Title 12 - Environmental Protection

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