Engine Technology Forum Defends SCR and DEF Amid EPA Guidance Adjustments

Event summary

  • Engine Technology Forum held a webinar on April 20, 2026, clarifying the role of SCR and DEF in diesel engines amid recent EPA guidance.
  • SCR and DEF systems have been standard in millions of engines since 2010, enabling 95% reductions in NOx and particulate matter.
  • DEF supply chain in North America is robust, with 1.46 billion gallons projected for consumption in 2026.
  • EPA guidance issued in August 2025 and March 2026 provides manufacturers with flexibility in compliance strategies without weakening emissions standards.

The big picture

The Engine Technology Forum's webinar underscores the critical role of SCR and DEF in meeting stringent emissions standards, particularly in the heavy-duty sectors. The recent EPA guidance aims to improve real-world operability without rolling back emissions standards, reflecting a broader trend toward balancing environmental regulations with industrial efficiency. The mature DEF supply chain and the proven effectiveness of SCR systems position them as key components in the future of clean diesel technology.

What we're watching

Regulatory Flexibility
How EPA's guidance will affect manufacturers' compliance strategies and the pace of adoption of alternative technologies.
Supply Chain Stability
Whether the DEF supply chain can maintain reliability amid potential regulatory changes and market demands.
Technological Leadership
The extent to which SCR and DEF systems will remain the preferred solution for emissions control in heavy-duty applications.