10 December 2004

The California Air Resources Board (ARB) approved a mandatory software upgrade—so-called “chip reflash”—program for affected heavy-duty diesel engines. Owners and operators of heavy-duty trucks, buses, and other vehicles that use model year 1993-1999 heavy-duty diesel engines will be required to have an upgraded version of software in their engine’s electronic control module (ECM). The mandatory program replaces the former voluntary effort.

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The regulation affects an estimated 58,000 engines in California, only 14,000 of which (24%) have been reflashed. The rule also applies to some 300,000 to 400,000 out-of-state vehicles that drive through California. Under the mandatory program, all heavy-duty engines have to be reflashed by the end of 2005, and medium-duty engines by the end of 2006. The cost of the reflash is to be covered by the engine manufacturer.

The ARB estimated that the chip reflash would result in NOx emission reduction from California vehicles by 30 tons a day, and from out-of-state vehicles on California roads by an additional 6-9 tons per day.

The introduction of electronically controlled engines also created a market for illegal third-party “diesel chip” software for heavy-duty diesels, which provides superior fuel economy at the expense of higher NOx. The scale and emission impacts of the problem remain largely unknown.

California ARB: Software Upgrade Page