Diesel Idling Restriction Ordinance

The purpose of ordinance P-21 is to protect public health and the environment by reducing emissions of toxics and criteria pollutants while also conserving fuel. Affected vehicles are required to limit idling to no longer than five minutes under most circumstances.

Vehicles Affected by the Ordinance

The ordinance applies to diesel-fueled commercial motor vehicles that weigh more than 14,000 pounds operating in Maricopa County, regardless of where the vehicles are registered. It applies to vehicles designed to operate on public highways and powered by a diesel engine.

Penalties for Non-Compliance

The driver of the vehicle who violates this ordinance is subject to a minimum civil penalty of $100 for the first violation and $300 for a second or any subsequent violation.

Exceptions to the Idling Restrictions

  • Drivers stuck in traffic due to congestion or weather issues.
  • The main engine is being idled during Department of Transportation mandated rest periods (US 49 CFR Part 395, AZ R17-5-202).
  • The main engine is being idled in order to conform to the manufacturer's "warm up" or "cool down" specifications.
  • The main engine is being idled for maintenance or diagnostic purposes.
  • The main engine meets ALL of these listed criteria:
    • Provides a necessary power source for mechanical operations other than propulsion
    • Involves a Power-Take-Off (PTO) mechanism
    • Powers the:
      • Loading/unloading of cargo
      • Mixing or processing of cargo
      • Temperature control of cargo
      • A mechanical extension to perform work functions
  • Passenger buses (including school buses), which are being idled in order to provide heat or air conditioning necessary for comfort/safety may idle for up to:
    • 30 minutes during any 60 minute period
    • When temperatures exceed 75 degrees Fahrenheit, a passenger bus is allowed to idle up to 60 minutes during any 90 minute period
    • For emergency and/or law enforcement purposes

Last reviewed 29 March 2019