321.433  Sirens, whistles, air horns, and bells prohibited.
  1.  A vehicle shall not be equipped with and a person shall not use upon a vehicle any siren, whistle, or bell, except as otherwise permitted in this section or any other provision of law.
  2.  It is permissible but not required that any commercial vehicle be equipped with a theft alarm signal device which is so arranged that it cannot be used by the driver as an ordinary warning signal.
  3.  Any authorized emergency vehicle may be equipped with a siren, whistle, air horn, or bell capable of emitting sound audible under normal conditions from a distance of not less than five hundred feet. 
  4.  An authorized emergency medical services program, fire department, or law enforcement agency may equip one or more vehicles with an air horn or a low-frequency siren.
  5.  An official fire department vehicle, emergency medical services program vehicle, or law enforcement vehicle owned by the state, a municipality, as defined in section 670.1, or a corporation providing emergency medical services, that was purchased, delivered, or refurbished on or after July 1, 2022, excluding an all-terrain vehicle or a special service vehicle, shall be equipped with an electric or electronic siren capable of emitting at least two distinct siren tones, and one or more compatible siren speakers.
  6.  An authorized emergency vehicle’s siren, whistle, air horn, or bell shall not be used except when the vehicle is operated in response to an emergency call, an incident dangerous to the public, an official training exercise, in a parade or designated public service event, for maintenance or demonstration purposes, or in the immediate pursuit of an actual or suspected violator of the law, and the driver of the vehicle shall sound the siren, whistle, air horn, or bell when the driver reasonably believes necessary to warn pedestrians and other drivers of the approach of the vehicle.
  7.  A towing or recovery vehicle, unless owned by the state or a municipality, as defined in section 670.1, shall not be equipped with a siren.
  8.  For purposes of this section:
  a.  “Electric siren” means an audible warning device that produces sound using an electric motor with an attached rotating slotted or perforated disc.
  b.  “Electronic siren” means an audible warning device that produces sound electronically using amplifiers and electromagnetic speakers.
  c.  “Low-frequency siren” means a siren that produces low-frequency sound waves and is used in addition to an electric or electronic siren.
[C39, §5034.42; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §321.433]
98 Acts, ch 1080, §4; 2021 Acts, ch 97, §7, 9; 2022 Acts, ch 1087, §8, 11
Referred to in §321.231, 321.231B, 805.8A(3)(ag)
For applicable scheduled fine, see §805.8A, subsection 3 
Section amended