27 January 2004

The California Air Resources Board (ARB) has suspended verifications of two diesel particulate filter systems: the DPX™ filter by Engelhard Corporation and the CRT™ filter by Johnson Matthey. This step has been taken when, after a lengthy dispute, the ARB and the emission control manufacturers could not reach an agreement on the requirements of the California verification procedure.

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The de-listed diesel particulate filters were verified in 2001 based on an “interim” version of the ARB verification procedure. The document—called the “Verification Procedure, Warranty and In-Use Compliance Requirements for In-Use Strategies to Control Emissions from Diesel Engines”—has been developed by the ARB as the basis for the quantification of emission reduction by control systems intended for retrofitting of diesel engines under the California Diesel Risk Reduction Program.

The final version of the verification procedure incorporated several additional provisions, not included in the interim version, which were opposed by manufacturers. The central unresolved issue has been the ARB’s warranty requirements, under which emission control manufacturers must provide warranty coverage not only for their verified device—such as a particulate filter or catalytic converter—but also for the diesel engine on which the device is installed.

“We are trying to arrive at an acceptable solution to the warranty liability issue with ARB and other stakeholders,” Johnson Matthey told DieselNet. Hopefully, a position can be reached where the verification can be reinstated.

The ARB Executive Orders for the de-listed filters remain in place, so they can be legally sold and fitted to vehicles in California. However, they no longer qualify for use under mandated rules, such as the California transit bus fleet regulation.