Voluntary Program - Software Upgrade for Diesel Trucks

This page last reviewed May 31, 2011

Voluntary Software Upgrade Program

This page contains information about the Voluntary Program for installing the Low NOx Software in diesel trucks.


At the March 25, 2004, meeting of the Air Resources Board, the Board approved the Voluntary Program for Software Upgrade and the proposed Software Upgrade regulation as a backstop to the Voluntary Program. The Board directed that initial reporting of  the Low NOx Rebuild Software installation status should be quarterly. The Board moved up the timeline for 100 percent of the eligible engines to be reflashed - calling for that to happen by 2008 (instead of 2010). The Board also directed staff to convene a Software Upgrade Voluntary Program Coordination Group, which will include environmental representatives, dealers, and other stakeholders interested in tracking the progress of the Voluntary Program.

Voluntary Software Upgrade Program Continues for DDC Engines

At the December 9, 2004, meeting of the Air Resources Board, the Board approved continuing the Voluntary Software Upgrade Program for owners of Detroit Diesel engines. If your eligible engine is a DDC, installation of the low NOx software is voluntary; however, if reflash progress is not significant, then owners of DDC engines would also be subject to regulation. Owners of other eligible engines must install the low NOx software as required by the regulation approved at the March 25, 2004, board meeting.

Important Links

Engine Manufacturer Letters to Dealer Regarding the Voluntary Program

Most 1993-1998 model year diesel engines that are electronically-controlled have low NOx software available.
Letter to Independent Heavy-Duty Engine Rebuilders (pdf - 25K)

California Trucking Association (CTA)

ARB and CTA worked together to assure the success of the Voluntary Software Upgrade Program.