Skip the auto shop - Our mechanics make house calls

Q: What Are California's Emissions Standards?

asked by on

What are California's emissions standards?

The emissions standards for California are quite extensive. The state standards are more stringent than the federal standards and they cover a wide range of vehicle emission types. A growing number of other states, and foreign countries, are adopting California’s emissions standards for their areas.

In general, California emissions standards are divided into three levels: LEV (Low Emission Vehicle)/Tier 1, LEV II/Tier 2, and LEV III/Tier 3.

LEV standards are applied to vehicles through model year 2003. LEV II standards apply to model years 2004 - 2010. LEV III standards apply to model years 2015 - 2025.

Tier 1 vehicles are divided into three separate groups:

  • Passenger cars
  • Light duty trucks below 6000 GVWR
  • Light duty trucks above 6000 GVWR

Tier 2 encompasses all Tier 1 vehicles and includes light duty trucks above 8500 GVWR

Tier 3 replaces Tier 2

Within the LEV set of standards, there are further classifications of emissions by vehicle type. These include:

  • Transitional Low Emission Vehicles (TLEV)
  • Low Emission Vehicles (LEV)
  • Ultra Low Emission Vehicles (ULEV)
  • Super Ultra Low Emission Vehicles (SULEV)
  • Zero Emission Vehicles (ZEV)

California emissions standards cover much more, like heavy duty engines, off-road diesels, marine engines, and locomotives. What I’ve covered here is just a thumbnail sketch of the current legislation.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: What Types of Metals Are Used to Make Exhaust Systems?

Chances are good that your exhaust system is made from 400-series steel. Cast iron is used for the exhaust manifold (stock). Aluminized steel is often used in aftermarket exhaust systems. In addition, a wide range of other metals can be...

Q: Car failed emissions test

Your truck can fail an emissions test for a number of reasons. If I knew the results of the inspection I could give you some common causes of this failure. If the vehicle failed the visual check then there may...

Q: Car Loses Power And Puffs Out Large Amounts Of Black And Grey Smoke, First Backfire Was Very Loud, with sulfur/exhaust fumes smell.

Hello There, This is quite likely a sign of a failing or clogged catalytic converter. The catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this is clogged, this...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...