Cummins Inc. will voluntarily recall about 500,000 plus model year 2010-2015 heavy and medium duty trucks, U.S. Environmental Protection Agency (EPA) declared on Tuesday.

The recall will soon replace a faulty emissions control systems element which causes excess emissions of nitrogen oxides (NOx), as stated by the EPA. This recall is that the largest voluntary truck emissions remember thus far. The difficulty Cummins is acting to correct is the consequence of a defective part -- perhaps not a defeat device, like the application illegally employed by Volkswagen to pass U.S. emission evaluations.

"Here is the way it's supposed to work. Our follow up testing attempts to make sure that pollution controls work through an engine's life. And, if they don't, then companies step up to put things right."

A spokesman for Cummins said the recall was"in the best interests of our client and the environment," The recall will likely be rolled out in two phases, beginning with heavy duty trucks this month and medium-duty trucks at March

Medium- and - heavy-duty categories contain vehicles ranging from bigger pickup trucks to vocational vehicles into large rigs. A previous recall, already underway, concerned about 232,000 Dodge Ram 2500 and 3500 pickup trucks, bringing the whole number of vehicles that are affected to approximately 770,000.

Cummins will recall the remaining affected vehicles in two stages. The company is going to contact owners with directions regarding how and when to receive their truck fixed. Owners should contact Cummins for further specifics regarding the products that are affected and recall program.

This recall is the largest voluntary truck emissions recall thus far, according to EPA.

The trucks being recalled are equipped with selective catalytic reduction (SCR) programs developed to control NOx emissions. The SCR catalysts that'll be substituted via the recall were found to be less durable than is required, degrading in a couple of years instead of controlling NOx contamination for the regulatory total operational life of the truck. The recall will replace these SCR system parts. The whole useful life span of medium-duty automobiles is 185,000 miles or ten years (whichever is first), and also the full useful life of heavy-duty vehicles is 435,000 miles or ten years.

The problem was discovered through government supervision programs that test vehicles for compliance with emissions standards throughout their useful life. Initial testing identified high NOx emissions from trucks equipped with Cummins motors. EPA and CARB shared outcomes with Cummins, which consented to conduct the voluntary recall after the organization's own followup testing confirmed that deteriorating elements inside the SCR system were causing emissions to exceed Federal and California pollution criteria.