Truck Stop and Fuel Marketers Oppose EPA's DEF Regulation Changes

ALEXANDRIA, Va. – Two industry groups representing truck stops, travel centers, and fuel marketers are pushing back against proposed changes to regulations surrounding Diesel Exhaust Fluid (DEF). NATSO and SIGMA stated concerns that the U.S. Environmental Protection Agency's (EPA) proposal to fundamentally alter the regulatory backdrop for DEF is premature.

The EPA's proposal would eliminate mandatory vehicle derating—a reduction in engine power—as an inducement to meet NOx emissions requirements starting with the 2029 model year. NATSO and SIGMA argue this change could lead to consumer confusion and threaten DEF availability while increasing its price.

According to NATSO and SIGMA, prior guidance issued by the Trump administration is still being implemented and its benefits have yet to be fully realized. This previous guidance, issued in 2025 and early 2026, called for large-scale DEF software updates, the use of NOx sensors instead of urea quality sensors, and adjustments to the power reduction schedule. These measures are intended to reduce false warnings, unnecessary repairs, and instances where functional trucks are taken out of service.

"Allowing ample time for existing guidance to penetrate the market will minimize unnecessary and punitive deratements for diesel vehicles while ensuring that Selective Catalytic Reduction technology remains an essential part of every truck manufacturer's investment and compliance strategy," said David Fialkov, head of government affairs for NATSO and SIGMA.

The organizations highlighted DEF technology as a significant environmental success story for liquid fuels in the trucking sector, enabling emissions reductions through innovation within the existing framework. They expressed a desire to work with the EPA on future reforms to ensure they are targeted and evidence-based, avoiding negative impacts on DEF availability or cost.