NATSO, representing truck stops and travel centers, and SIGMA: America’s Leading Fuel Marketers, questioned the Environmental Protection Agency’s (EPA’s) proposal to fundamentally alter the regulatory backdrop for diesel exhaust fluid (DEF) before the Trump Administration’s previous, thoughtful Guidance documents are implemented and the benefits realized. “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.
EPA’s proposal would eliminate deratement as a mandatory inducement to satisfy NOx emissions requirements beginning in Model Year 2029.
This proposal will invite consumer confusion and threatens to decrease DEF’s availability and increase its price. There is no reason to undermine the common sense measures the Administration has already taken.
Prior to this proposal, the Trump Administration initiated a series of actions that — when fully implemented — can resolve consumer concerns surrounding diesel exhaust fluid and the operational reliability of DEF-related equipment. NATSO and SIGMA strongly support those efforts. The first Guidance documents issued in 2025 and early 2026 call for large-scale DEF software updates, the use of NOx sensors instead of urea quality sensors, as well as adjustments to the power reduction schedule. This is precisely what the market needed, but it takes time for the industry to realize the benefits: fewer false warnings and unnecessary repairs, and fewer situations where a functioning truck is unnecessarily
taken out of service.
“While the Administration’s impatience is understandable, we believe it is counter-productive to prematurely disrupt that process when allowing it to proceed would negate the need for today’s DEFrelated actions,” Fialkov said.
DEF remains an essential product for the reliable operation of commercial trucks regardless of whether EPA mandates that trucks derate. OEMs seeking to comply with EPA’s emissions targets have integrated the use of DEF into the overall fabric of today’s system designs.
“The widespread adoption of DEF technology represents perhaps the most significant environmental success story for liquid fuels in the trucking sector,” David Fialkov said. “It is an important demonstration that emissions reductions can be achieved through targeted innovation within the existing liquid-fuels framework.”
NATSO and SIGMA support the benefits that DEF and SCR technology have delivered to emissions reductions and fuel economy. NATSO and SIGMA look forward to working with EPA to ensure that any further reform efforts are carefully targeted and evidence-based to avoid diminishing DEF’s availability or increasing its costs for consumers.
