Sun Prairie, WI Environmental Rules: Vehicle Idling Restrictions (2026)

050(B) makes it unlawful to cause or permit a motor vehicle's engine to idle for longer than five consecutive minutes while the vehicle is stopping, standing, or parked on any highway or place open to the public. The registered owner of the vehicle is solely liable for a violation, even if someone else was driving at the time, and a city-owned vehicle's driver, rather than the city, is liable for a violation involving a municipal vehicle. Subsection D lists five specific exceptions: idling is allowed when the ambient temperature is below 20 degrees Fahrenheit or above 90 degrees Fahrenheit; to run a defroster, heater, air conditioner, or other equipment needed to prevent a health or safety emergency, including providing shelter; for testing, servicing, repair, or diagnostic work; to operate auxiliary equipment the vehicle was built for, such as a refrigeration unit, lift, crane, pump, drill, hoist, or concrete mixer, other than for hauling goods; and while stuck in traffic conditions the driver cannot control, including congestion, a red light, a passing train, a construction zone, or a police officer's direction. Any police officer or parking enforcement officer can enforce the section.