EPA demands DEF failure data from diesel makers. Investigation could force recalls and software fixes for engines already on U.S. roads. 30-day deadline set.

Maintaining optimal performance and ensuring compliance with emissions standards go hand in hand for operators of diesel trucks. Diesel Exhaust Fluid (DEF) is a critical component in achieving both.

Manufacturers' required DEF derates will soon be less severe. Current equipment may enter limp mode and slow to 5 mph, or stop altogether until a DEF fault is cleared. The EPA's new guidance for ...