DOJ won’t pursue jail time for diesel deleting; civil penalty risk to remain

The Department of Justice Environment and Natural Resource Division has decided it will no longer criminally prosecute mechanics who engage in diesel deleting and cheating, the agency announced via X on Wednesday. This was directed by Deputy Attorney General Todd Blanche. The act of tuning/reprogramming diesel engines or installing aftermarket devices to circumvent diesel emissions systems can still incur civil penalties under Clean Air Act statutes.

“Today, @TheJusticeDept is exercising its enforcement discretion to no longer pursue criminal charges under the Clean Air Act based on allegations of tampering with onboard diagnostic devices in motor vehicles…

DOJ is committed to sound enforcement principles, efficient use of government resources, and avoiding overcriminalization of federal environmental law. In partnership with the @EPA, DOJ will still pursue civil enforcement for these violations when appropriate.”

This means the DOJ will also drop any ongoing criminal prosecution related to diesel defeat devices. 

Diesel cheating can still cost you

Tuning diesel engines can improve fuel efficiency and performance, and can remove the need for diesel exhaust fluid and expensive aftertreatment maintenance, though the act obviously creates more emissions. But those considering any emissions deleting or tuning that go against the Clean Air Act should remember the severe civil penalties remain on the table.

According to Clean Air Act Title 40, Ch. 1, 1068.101, tampering is defined as “remov[ing] or render[ing] inoperative any device or element of design installed on or in engines/equipment in compliance with the regulations” before or after sale. Each violation can incur a $45,268 penalty per tampered engine and $4,527 per event or defeat device sale. Repair and emergency modification are excluded, according to the code.

And regardless of who is in office, the government will do everything within its power to take Americans’ money.

Two weeks prior to the DOJ announcement, Meyer Distributing, Inc. settled with the EPA to the tune of $7.4 million civil penalty. The performance auto part supplier was reported to have sold over 90,000 aftermarket defeat devices. The EPA said that is the pollution equivalent to an additional 700,000 vehicles on the road.

Will the current administration go after small fish modifying a diesel car or truck? Probably not, as Zeldin has stated stopping defeat devices is not an EPA priority. He also has relaxed standards on when DEF faults will trigger a truck or farm equipment going into limp mode.

But circumventing emissions systems can cause problems even if the feds don’t find out.

In our previous reporting, Steve Hoke, president of Diesel Emissions Service (DES), noted bypassing the emissions system can cost more than regular maintenance.

“I’ve heard of some truck owners spending $5,000 to have an EGR deleted when they could have just replaced it for $1,200,” he said in 2025. “And the thing is, when you use a tune to cheat an emissions system, but still leave the physical components like the DPF intact, it’s still having to catch all of that soot and ash. That’s still going to cause major problems down the road.”

In short, it’s bad business for fleets and reputable shops to engage in emissions tampering.

What spurred the change?

This announcement comes two months after President Donald Trump pardoned a Colorado shop owner, Troy Lake, Sr., who served seven months in prison for diesel deleting.

According to the DOJ in Dec. 2024, then run by President Joe Biden (or an autopen), Lake directed his employees to disable the OBDs on 344 heavy-duty commercial vehicles such as school buses and fire trucks so they would not detect emissions malfunctions. The 65-year-old owner of Elite Diesel Service, Inc. in Windsor was sentenced to one year and one day in federal prison and he and the shop were assessed fines totaling $52,000. The DOJ named eight co-conspirators, who were assessed penalties totaling $920,500.

Lake, who lived in Cheyenne, Wyoming, maintained that these essential vehicles were altered to reliably perform their civic duties in the harsh winters near the Wyoming-Colorado border.

Wyoming Sen. Cynthia Lummis was instrumental in getting EPA Administrator Lee Zeldin and Trump to notice Lake’s situation. Last October, she also introduced a bill called the Diesel Truck Liberation Act.

“The Biden EPA threw Troy Lake and other mechanics in prison for keeping school buses, fire trucks, and ambulances running in cold, harsh climates,” Lummis stated in the release. “When Washington bureaucrats can make you a criminal without Congress ever voting on it, we have a huge problem. I want this overreach to end. Democrats weaponized the EPA to wage war on rural America, and we cannot let that happen again. This legislation is the first step toward justice and sanity.” 

That bill went nowhere, but at the same time, the defense team for RPM Motors owner Tracy Coiteux argued upon appeal that their client’s conviction and sentence of three years of probation was unjust because the Clean Air Act does not say onboard diagnostics system software needs to be maintained, according to a report by CBS. She and her husband Sean Coiteux had pleaded guilty to tampering with a monitoring device.

CBS reported Adam Gustafson, assistant attorney general for DOJ’s environmental arm, allegedly believed this new defense theory was sound enough to forgo pursuing criminal charges for diesel tampering.

On the same day the DOJ made their announcement, the criminal case against  Coiteux was dismissed. Given the civil penalties are still in place, it’s likely the shop owners are still on the hook for their $10,000 fines.