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Why Retrofit?

Reasons to retrofit an in-use diesel vehicle with a CARB-Verified system

For almost two decades, DPF systems have been successfully used to retrofit in-use diesels powering tens of thousands of in-use on-road vehicles such as transit buses, school buses, refuse trucks, delivery trucks, intermodal trucks, utility trucks, municipal vehicles, recycling trucks, shuttle buses and more. Retrofit systems are a mature robust technology to achieve immediate and effective emissions reduction on in-use diesel-powered vehicles and equipment.

ESW Group has the largest portfolio of CARB-verified retrofit systems which cover almost every application. Although diesel engines produced in 2007 and thereafter are equipped with OEM emission control systems, retrofit still is a cost-effective way to continue to reduce emissions from older vehicles that are not easily replaced or are of limited use and replacement is not cost effective (for your post-2007 engines, Skyline Emissions is your best choice).

  • CARB compliance

    • Current rules in California cover on-road model years up to 2007.  As of January 1, 2023, California’s DMV will no longer register on-road trucks and buses that do not have a complete NOx and PM aftertreatment system. In NOx exempt areas or certain agricultural applications PM-only retrofits are still a path to compliance.

  • State of Oregon Incentives

  • Supplemental Environmental Projects (SEPs)

    • If your company has been found to have violated federal air quality regulations, one of the ways to make up for the excess emissions caused by your company is through a Supplemental Environmental Project (SEP) with the U.S. EPA.

    • Diesel retrofits can be an effective way to create new emissions reduction: they are a proven technology, use traceable processes in their implementation, and are scalable.


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