- The EPA plans to end a requirement that diesel engines use pollution-reducing additives
- The agency’s head is asking automakers to act right away before the new rules
The Environmental Protection Agency is calling on automakers to eliminate software modes that cause some diesel-powered pickup trucks to lose power when they run low on diesel exhaust fluid (DEF).
If you own a diesel-powered truck, that sentence made perfect sense to you. If you don’t, it may require some explanation.
Related: What Is Diesel Gas?
Modern Diesel Engines Use an Additive to Cut Smog
- Diesel exhaust fluid helps remove nitrogen oxide from exhaust
- Some engines go into limp mode when they run out
Diesel engines produce high levels of nitrogen oxide (NOx), a greenhouse gas and a significant component of the smog that once plagued American cities. However, automakers can reduce NOx by asking owners to add a solution of urea and deionized water, called DEF, to their engines.
To encourage them to use DEF, automakers routinely build in software that causes truck engines to lose power if they run out of the fluid – so-called “limp mode.”
Federal law never actually required DEF. But it required automakers to restrict the pollutants created by the vehicles they sell.
Until recently.
Last month, the EPA announced that it would stop enforcing emissions rules affecting cars, power plants, and other sources of smog.
The move came just weeks after the Department of Transportation stopped enforcing all federal fuel economy standards.
Related: What Is a Diesel Engine?
Now, EPA Administrator Lee Zeldin is asking automakers to remove the limp mode from their trucks. Speaking at the Iowa State Fair, Zeldin said, “The current DEF system is unacceptable. It is unacceptable that farmers, truckers, construction workers, and many other small businesses continually experience failures of diesel-powered equipment when they need it most — costing millions of dollars in lost productivity.”
The EPA will rewrite regulations to require manufacturers to remove limp mode “starting with model year 2027,” the agency said. But Zeldin is encouraging automakers to remove the setting ahead of the new rules.
“This ensures that bureaucratic steps do not delay manufacturers’ ability to put solutions into the field,” the EPA said in a statement.
