Diesel DEF Limp Mode Anxiety Be Gone: EPA Rolls Back More Environmental Protections

Just two weeks ago, the head of the Environmental Protection Agency (EPA) made an extraordinary announcement: Pollution from global warming would no longer be considered a threat to public health.

Known as the “endangerment finding,” the Obama-era policy empowered federal officials to regulate pollution caused by vehicles and power plants. It also led to electric vehicle subsidies that boosted the nascent EV industry, including companies like Tesla. But the 15-year-old policy is no more, the EPA announced on July 29.

Today, EPA Administrator Lee Zeldin once again made it clear that he’s on a mission to end the regulation of greenhouse gas emissions. In a speech at the Iowa State Fair, Zeldin told automakers to do away with certain vehicle standards for reducing pollution.

EPA Rolls Back Diesel Emissions Regulation

In this case, Zeldin wants them to stop installing software that causes many vehicles (especially trucks) to lose power when they have low levels of diesel exhaust fluid (DEF). This is referred to as “limp mode.”

The fluid and its systems, which reduce harmful nitrogen oxide emissions from diesel exhausts, will still technically be required. But, by removing the requirement that a vehicle go into limp mode without the fluid, Zeldin removed a key method of enforcing that rule. He called the change a win for everyday drivers and those working in agriculture.

Change Praised by the Agriculture Industry

At the Iowa State Fair, Zeldin found many sympathetic ears for the policy change. Agricultural workers have long voiced frustration with modern diesel emissions systems. By forcing vehicle makers to install a fail-safe that causes vehicles to lose power without DEF, many of them experience a loss of productivity.

Indeed, Zeldin claimed the change will immediately improve productivity among farmers. If the vehicle detects low levels of DEF (the emissions-reducing fluid), it can still be operated for up to 36 hours without issue. After that, the vehicle will gradually begin to slow down in torque.

The move was immediately applauded by those working in the agricultural sector.

“This is a positive step and maybe a formative step toward saying that having these emission standards on farm or off-road equipment is not critically necessary,” Ben Reinsche, owner of Blue Diamond Farming Company in Jesup, Iowa, told AgWeb. “There are so many other things farmers can do that are planet positive, like using conservation and sustainability practices.”

Limited Limp Mode

Even if some automakers wanted to maintain “limp mode” for the sake of reducing emissions, they won’t be allowed to continue doing it. Starting in model year 2027, diesel trucks can’t have a “limp mode” that happens immediately when they run out of DEF. Systems have to, at a minimum, provide 4,200 miles or 80 hours of run time before reducing power.

That means most drivers will likely use this new program to run their diesel vehicles without DEF for some time. This, of course, will save them a few dollars — while heavily increasing airborne pollution.

This is likely to be especially true for many commercial truck drivers, who could potentially cut their costs quite a bit. Not to mention the fact that it will likely remove the hefty fines for removing the DEF systems that many companies — commercial and consumer — have faced, as The Drive has reported.

Given the continued increase of natural disasters linked to climate change, conservationists will be less pleased about the rule change. After all, the primary mission of the EPA, as stated on its own website, is “to ensure that Americans have clean air, land, and water.”