Diesel engines will no longer be forced to power down suddenly due to problems with a machine’s diesel exhaust fluid (DEF) system following new guidance announced by Environmental Protection Agency (EPA) Administrator Lee Zeldin last week at the Iowa State Fair. 

The guidance urges engine and equipment manufacturers to revise DEF system software in existing vehicles and equipment to prevent sudden speed and power losses, giving operators more time to repair faults without impacting productivity or safety. 

“What I’ve heard in my travels from farmers and truckers, school bus operators and more is a concern with the deratement of their diesel engines when it comes to DEF. It happens really quickly, and it doesn’t just happen because there isn’t ...