Among the host of legal challenges related to the October 2002 emissions standards, Caterpillar has filed a petition to overturn the EPA’s certification of Cummins’ ISX engine.

According to published reports, Caterpillar has filed a petition in a federal appeals court, claiming that Cummins’ engines rely on devices that bypass emissions-reduction technology.
Cummins is currently the only company with an EPA-certified engine that meets the new standard. Caterpillar has submitted an engine for certification, although it will not meet the new standard despite lower emissions levels.
Caterpillar claims the auxiliary emission control device technology, or AECD, that Cummins uses to protect its engines under certain extreme operating conditions is a “defeat device” like those that prompted the EPA to sue engine makers several years ago. In the previous case, which led to the consent decree pushing up the emissions deadline from 2004 to this October, engine makers used this technology to enhance engine performance while trucks were on the open highway. Cummins say the EPA has specifically approved the use of AECDs to prevent engine damage under extreme conditions such as at high temperatures or pulling a heavy load in hilly terrain.