(Radio Iowa) – The head of the U.S. Environmental Protection Agency has used a trip to Iowa to announce changes in federal regulations for vehicles that run on diesel.

For a couple of decades tractors, trucks and other diesel-powered vehicles have had systems that inject a fluid into the exhaust to reduce nitrous oxide emissions, but sensors immediately slow down and even stall the engine when that fluid runs out. EPA Administrator Lee Zeldin said it means diesel equipment shuts down unnecessarily, “which has led to so much in lost money for Iowa farmers and truckers and so much more.”

Under new EPA guidelines, diesel truck manufacturers are to change the technology by the 2027 model year so vehicles that run out of that emission-related fluid won’t have sudden power losses.

EPA Administrator Lee Zeldin speaks during stop at Nevada, Iowa, business. (RI photo)

Zeldin is reluctant to talk about another fuel-related issue — the EPA’s proposed ethanol and biodiesel production levels for the next two years. “A lot of people were happy with the numbers we came out with and that was a strong, early sign, however understanding that every single decision that I make — whether I say yes or no — is going to result in a lawsuit from whoever’s on the opposite side I’m going to be very clear: I’m not prejudging the result of this rule making,” Zeldin said. “We’re going through the public comment period and we’re looking to make the right decision on the other end.”

The end of the October is when the EPA is tentatively scheduled to announce the final ethanol and biodiesel production rules for 2026 and 2027. Senator Joni Ernst, who hosted Zeldin on his trip to Iowa, said the EPA’s proposed 8% jump in biofuels obligations is an exciting prospect. “I’ve heard from so many of our farmers across Iowa, the biofuels producers,” Ernst said. “They are really glad that EPA and President Trump have been supportive.”

Ernst and Zeldin spoke with reporters after spending time at the State Fair, speaking at a forum in Ames for entrepreneurs and touring Mid-States Companies in Nevada. The head of the Small Business Administration was also on the trip.