Maricopa County, AZ Noise from Specific Sources: Car Alarm Limits (2026)

Maricopa County Ordinance P-23, the county's Noise Ordinance, generally bans noise loud enough to disturb the peace or be heard from within a closed residential structure within 500 feet of the source, but it carves out a specific window for alarms. The Exemptions section states that 'noise emanating from alarms and other warning devices not operated continuously for more than thirty minutes per incident' is not a violation, covering car alarms alongside home security and burglar alarms. Once an alarm runs past thirty minutes in a single incident, the exemption ends and the noise can be cited under the ordinance's general prohibitions the same as a stereo or a loud party.

The Administrator, defined as the Board of Supervisors or its authorized representative, including the Maricopa County Sheriff's Office, enforces the ordinance and is authorized to issue a written warning first, ordering the offending noise to cease within a specified time. If the noise doesn't stop within that window, the responsible person is guilty of a misdemeanor. Conviction carries a fine of up to $300 for a first offense, $500 for a second, and $750 for a third or later offense, with every day the violation continues charged as a separate offense.

Cases are prosecuted in the Maricopa County Justice Courts. If the county has to send crews out repeatedly to abate a chronic noise nuisance, those abatement costs become a special assessment against the property and are collected the same way as other county charges. Because P-23 applies only in unincorporated Maricopa County absent an intergovernmental agreement, a car alarm dispute inside Phoenix, Mesa, Scottsdale, or any other incorporated city or town falls under that city's own noise code instead.