The EPA is escalating its response to consumer complaints regarding DEF system failures, announcing a new investigation aimed ...

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.

Diesel exhaust fluid (DEF) is nothing new. GM’s Duramax-powered Chevrolet Silverado and GMC Sierra 2500HD and 3500HD pickups have had used the stuff since 2011. So has Ford’s F-Series Super Duty.

Long-haul truckers and diesel engine enthusiasts had to rethink their entire operations in 2010 when the Environmental Protection Agency mandated selective catalytic reduction technology. Selective ...