U.S. Court of Appeals for the District of Columbia Circuit ruled Tuesday that the Environmental Protection Agency made a mistake in passing an interim rule permitting Navistar to pay fines and continue selling heavy-duty engines that do not meet current diesel emissions standards.
Volvo Trucks North America and Mack Trucks sued EPA as a result of the interim ruling. The court ruled in their favor, noting that the agency violated the Administrative Procedures Act by issuing the interim final rule.
Navistar chose to develop an in-cylinder emissions-controlling technology called advanced exhaust gas recirculation to reduce NOx emissions, but the company has not been able to meet the 0.20g standard with its heavy-duty engines.
The company had certified medium-duty engines, though, and their sales accumulated engine credits that allowed the sale of Navistar's heavy-duty engines. Navistar notified EPA last year that it could run out of credits before the heavy-duty engines were certified.