SACRAMENTO, CA — The Engine Manufacturers Association (EMA) went to court April 22 in California to block mandatory engine software upgrades to meet state pollution standards, reports Green Car Congress. The EMA is representing four diesel engine manufacturers (Caterpillar, Cummins, Mack Trucks, and Volvo) in this action to oppose implementation of a settlement between the OEMs and the California Air Resources Board (CARB). The genesis of this particular conflict was in 1998, when CARB engineers working with EPA discovered that diesel manufacturers were using dual calibrations in their electronic timing systems on heavy-duty engines produced between 1993 and 1998. An investigation revealed that since the early 1990s the manufacturers used the dual calibration devices (called "defeat devices") to cause the engines to perform one way when being tested for compliance and another under actual highway conditions, to recognize normal highway operation and then increase fuel economy at the expense of greater emissions of NOx. The U.S. EPA and CARB brought enforcement actions in 1998, and subsequently they reached a settlement with the manufacturers. Part of the settlement stipulated that the manufacturers would develop software to correct their onboard programs and eliminate emission increases, which would be "reflashed" onto every engine as they came in for rebuild or at the consumer's request. Through the negotiations with manufacturers, CARB said that it expected the rebuilds would occur between 300,000 to 500,000 miles, and allowed for voluntary compliance through 2008. However, many trucks were not brought in for rebuild until much later; from 750,000 to one million miles, which delayed compliance and vastly increased emissions. As a backstop to the volunteer program, the CARB adopted a regulation that would legally require upgrades to be installed by the manufacturers if the targets were not met. At the December 9, 2004, CARB Board hearing, the Board confirmed that all but one manufacturer failed to meet its voluntary program target and activated the regulation requiring manufacturers to promptly reflash all the engines. Several of the manufacturers balked, claiming that the agency was reneging on their agreement, and arguing that CARB could not arbitrarily change the rules. In a tentative ruling prior to hearing arguments, the judge denied the manufacturers' request that the initial April 30 compliance deadline be delayed while their lawsuit proceeds.