California Regulations

The new requirements from the California Air Resources Board (CARB) are intended to improve air quality by reducing particulate matter (PM) emissions from older vehicles, by replacing older engines and upgrading to a 2010 engine or newer.  On-road heavy duty diesel, dual fuel or alternative fuel vehicles with a gross vehicle weight rating (GVWR) greater than 14,000 pounds that are registered to be driven on the highway or originally designed to be driven on public highways are affected.

CARB Rule Brochure 
California Diesel Regulations 
On Road Agricultural

Clean Idle: California ARB (Air Resources Board) Idle Reduction Regulation (Effective January 1, 2008; Issued August 2007)


A new idle reduction regulation took effect in California beginning January 1, 2008. The new idle regulation applies to vehicles with a GVWR greater than 14,000 lbs. and licensed for on-highway operation, whether based in California or not.  The new idle regulation contains three main elements:  1) Heavy-Duty diesel engine manufacturers are required to have an automatic 5-minute idle shutdown timer that is tamper-resistant and non-programmable or in lieu of 2) an idle NOx emissions of 30 grams/hour (Clean Idle) which allows vehicles to idle indefinitely and 3)  Auxiliary Power Units require exhaust aftertreatment  i.e.  a diesel particulate filter.

Beginning January 2008 all Cummins on-highway products (ISX, ISM, ISL, ISC and ISB) will be Clean Idle certified.  2008 Cummins on-highway products will not require the automatic 5-minute idle shutdown timer.

Click here for a printable overview and FAQ

Cummins Clean Idle Overview presentation