The U.S. Environmental Protection Agency has issued new guidance directing diesel-engine manufacturers to revise software so that trucks, tractors and other equipment no longer face abrupt shutdowns when their Diesel Exhaust Fluid tanks run dry. Beginning with model-year 2027 vehicles and through voluntary updates to equipment already on the road, the policy aims to keep engines operating while still meeting nitrogen-oxide emissions standards imposed through Selective Catalytic Reduction systems. Under the rules for heavy-duty trucks, engines will initially lose 15 percent of torque for up to 650 miles or 100 hours after a DEF fault is detected. If the tank remains empty, torque is cut by 30 percent until 4,200 miles or 80 additional hours have elapsed, and only after 8,400 miles or 160 hours is speed limited to 25 mph. Non-road agricultural and construction equipment faces no performance penalty for the first 36 hours, followed by a modest torque reduction, replacing the previous regime that could idle machinery within four hours. EPA Administrator Lee Zeldin, who unveiled the measure alongside Small Business Administration chief Kelly Loeffler at the Iowa State Fair, said the change responds to complaints from farmers, truckers and other small businesses about costly downtime. The American Trucking Associations and farm groups praised the move, and the agency projects family farms could save about $727 million each year through reduced towing, repairs and lost productivity.