EvilCorporations.com  |  Environmental Investigation

1,447 Devices. Dirty Air. A Slap on the Wrist.

Filed February 26, 2024  |  EPA Region 5  |  DeKalb, Illinois

A small-town Illinois auto parts company sold nearly 1,500 illegal defeat devices over two years, knowingly gutting the pollution controls on diesel trucks that share the same air as the neighborhoods, schools, and playgrounds around every highway those trucks drive.

What Wehrli Actually Did

Wehrli Custom Fabrication, based at 231 Harvestore Drive in DeKalb, Illinois, describes itself as an aftermarket automotive parts manufacturer. Between January 2, 2018 and May 15, 2020, the company manufactured, sold, and installed EGR block plates, exhaust systems, ECM tunes or tuners, and other engine components on heavy-duty diesel vehicles.

Every single one of those products had one job: to disable, bypass, or render inoperative the emissions control systems that federal law requires diesel trucks to carry. Those systems, including diesel particulate filters (DPFs), exhaust gas recirculation systems (EGRs), diesel oxidation catalysts (DOCs), and selective catalytic reduction systems (SCRs), exist specifically to keep nitrogen oxides and particulate matter out of the air people breathe.

The EPA conducted a facility inspection on February 24, 2020, followed by a formal Information Request on August 4, 2020. Wehrli’s own purchase orders, sales invoices, and internal spreadsheets revealed the scale of the operation.

The Engine-Hacking Operation Nobody Talks About

Beyond selling physical parts, Wehrli went further: the company installed or modified software directly onto the engine control modules (ECMs) of at least 101 motor vehicles. ECMs are the computer brains of modern trucks. They coordinate every emissions control system on the vehicle. Modifying that software means deliberately instructing the truck to stop caring about pollution limits.

This is not a gray area or a regulatory technicality. The Clean Air Act calls this “tampering,” and it is specifically illegal under Section 203(a)(3)(A). Wehrli did it at least 101 times, on at least 101 separate vehicles, and the EPA’s own finding states the company “knowingly” did so.

The Penalty That Lets Them Keep Doing It

The EPA calculated that the maximum possible civil penalty per device or vehicle, for violations after November 2, 2015, is $5,580 (roughly two months of groceries for an average American family). With 1,447 defeat devices plus 101 tampered vehicles, the theoretical maximum penalty exposure was enormous. What Wehrli actually paid was a fraction of that.

The final settlement penalty was $267,680.21 (about what it costs to buy a modest single-family home in rural Illinois). That figure gets paid in four installments spread across a full year, with interest. The EPA acknowledged it factored in Wehrli’s “ability to pay” when arriving at this number.

Do that math: 1,447 defeat devices at $5,580 each represents a theoretical maximum of $8,074,260 (enough to fund a small-town public school for several years). Wehrli settled for about 3.3 cents on every dollar of maximum exposure. The system worked exactly as the company needed it to.

The Non-Financial Ledger

What the settlement dollar figure does not count

Every one of those 1,447 products Wehrli shipped had a specific destination: a diesel truck operating on real roads, near real people. Diesel trucks with intact emissions controls already push the boundaries of what clean air advocates consider acceptable. Trucks with their pollution controls deliberately removed emit far more particulate matter and nitrogen oxides, the two categories of diesel exhaust most directly linked to asthma attacks, cardiovascular disease, and early death.

The communities most exposed to heavy diesel truck traffic are almost never wealthy ones. Logistics corridors, freight routes, and distribution hubs run through working-class neighborhoods, communities of color, and agricultural towns. DeKalb, Illinois sits in a region with substantial industrial and agricultural truck traffic. Every defeat-device-equipped truck rolling through those corridors pumps out pollution that no certificate of conformity, no federal standard, and no consent agreement can retroactively undo.

The Quiet Devastation of “Knowingly”

The EPA’s consent agreement uses the word “knowingly” when describing Wehrli’s ECM tampering: the company “knowingly removed and/or rendered inoperative devices or elements of design.” That word matters. This is not a story about a company that made a mistake or misread a regulation. The law explicitly states that it is illegal for “any person knowingly to remove or render inoperative any such device or element of design after such sale and delivery to the ultimate purchaser.” Wehrli knew the law. Wehrli did it anyway. Wehrli did it 101 times on engine computers alone, and at least 1,447 times through its product catalog.

The word “knowingly” also follows Wehrli’s customers into every community those trucks serve. The consent agreement notes that Wehrli “knew or should have known” that its defeat device parts “were being offered for sale or installed for such use.” The company built a business model around that knowledge. The product catalog existed because there was demand, and Wehrli supplied that demand with full awareness of what the products would do to pollution controls and, by extension, to the air quality of every place those trucks operated.

A Settlement That Asks Almost Nothing

The EPA’s final order required Wehrli to pay $267,680.21 (roughly the annual salary of two experienced public school teachers) in four installments over the course of a year. The company also had to destroy remaining inventory of defeat devices by physically compacting or crushing them. Wehrli removed product listings and social media content promoting tampering services. Owner Jason Wehrli certified compliance with the Clean Air Act going forward.

None of those remedies address the 1,447 devices already in circulation. The consent agreement does not require Wehrli to notify the owners of the 101 vehicles whose engine computers were hacked. It does not create any fund to assist communities exposed to the elevated diesel emissions from those modified trucks. It does not require any ecological or public health monitoring. The harm already done to the air, to lungs, to neighborhoods is simply left in place, unaddressed, while the company writes a check that amounts to roughly 3 cents per dollar of maximum exposure.

Legal Receipts

Verbatim from the EPA Consent Agreement and Final Order

“Respondent manufactured, sold, offered for sale, and/or installed at least 1,447 aftermarket automotive parts that had a principal effect to bypass, defeat, render inoperative, or allow for the removal of one or more emission control devices or elements of design installed on or in a motor vehicle or motor vehicle engine. Respondent knew or should have known that such parts or components were being offered for sale or installed for such use or put to such use, in violation of Section 203(a)(3)(B) of the CAA.” EPA Consent Agreement and Final Order, Paragraph 32

“Respondent knowingly removed and/or rendered inoperative devices or elements of design installed in or on motor vehicles or motor vehicle engines in compliance with the CAA by installing or modifying software on ECMs installed on or in at least 101 motor vehicles or motor vehicle engines, in violation of Section 203(a)(3)(A) of the CAA.” EPA Consent Agreement and Final Order, Paragraph 33

“It is unlawful for ‘any person to manufacture or sell, or offer to sell, or install, any part or component intended for use with, or as part of, any motor vehicle or motor vehicle engine, where a principal effect of the part or component is to bypass, defeat, or render inoperative any device or element of design installed on or in a motor vehicle or motor vehicle engine in compliance with regulations under [Title II of the CAA], and where the person knows or should know that such part or component is being offered for sale or installed for such use or put to such use.'” EPA Consent Agreement and Final Order, Paragraph 21, quoting Section 203(a)(3)(B) of the Clean Air Act

“The CAA requires EPA to prescribe and revise, by regulation, standards applicable to the emission of any air pollutant from new motor vehicles or new motor vehicle engines which cause or contribute to air pollution, which may reasonably be anticipated to endanger public health or welfare.” EPA Consent Agreement and Final Order, Paragraph 10

“Respondent certifies that it has permanently destroyed all defeat devices remaining in Respondent’s inventory and/or possession, by compacting or crushing the defeat devices and all associated parts and components to render them useless.” EPA Consent Agreement and Final Order, Paragraph 43

Societal Impact Mapping

Public Health: Diesel Exhaust Has a Body Count

The EPA’s own statutory mandate describes these emissions as capable of causing or contributing to “air pollution which may reasonably be anticipated to endanger public health or welfare.” Those are not bureaucratic words. The specific pollutants that diesel emissions controls suppress, including particulate matter (PM) and nitrogen oxides (NOx), are among the most damaging categories of air pollution studied by public health researchers. Fine particulate matter penetrates deep into lung tissue and crosses into the bloodstream, contributing to heart attacks, strokes, lung cancer, and respiratory disease. NOx contributes to ground-level ozone, which triggers asthma attacks and degrades lung function.

The devices Wehrli sold were designed to disable diesel particulate filters (DPFs), exhaust gas recirculation systems (EGRs), diesel oxidation catalysts (DOCs), and selective catalytic reduction systems (SCRs). Each of those systems targets a specific category of harmful emissions. Removing all of them simultaneously means a modified diesel truck can emit orders of magnitude more pollution per mile than a compliant vehicle. Multiply that by 1,447 products across an unknown number of trucks on American roads, and the cumulative public health exposure becomes significant and entirely unquantified by the settlement.

The consent agreement contains zero provisions requiring any public health monitoring, no notifications to communities near freight corridors where these trucks operate, and no fund for medical screening or treatment. The $267,680.21 (roughly the annual cost of uninsured cancer treatment for fewer than three people) goes to the federal government’s general enforcement fund, not to any of the communities breathing the consequences.

Environmental Degradation: The Compliance System Exists for a Reason

Modern heavy-duty diesel engines are certified under a Certificate of Conformity (COC) issued by the EPA. That certification means the manufacturer tested the engine and confirmed it meets federal emissions standards. The entire system, the testing, the certification, the monitoring, relies on the assumption that the emissions control equipment actually stays functional. Wehrli’s business model attacked that assumption directly.

The regulatory framework under Part A of Title II of the Clean Air Act requires diesel engines manufactured after 2007 to carry onboard diagnostic systems (OBDs) specifically designed to detect when emissions components malfunction or are tampered with, alert the driver, and store the malfunction data. The ECM software modifications Wehrli performed on at least 101 vehicles effectively lobotomized that system, instructing the truck’s own computer to stop tracking or reporting emissions failures. The trucks then operated on public roads, emitting illegal levels of pollution with no warning light, no stored fault code, and no record that anything was wrong.

The atmospheric harm from elevated diesel PM and NOx emissions does not stay localized. Particulate matter disperses across regional airsheds, contributing to the ambient pollution loads that state and federal regulators track. Every defeat-device-equipped truck operating on the road represents a persistent, unmonitored source of excess emissions that degrades regional air quality for everyone, including communities many miles from the truck’s route. The consent agreement’s remedies address Wehrli’s inventory and advertising. They do not address the dispersed environmental degradation already caused.

Economic Inequality: Who Gets to Breathe Clean Air

The aftermarket diesel modification industry markets its products almost exclusively to truck owners who want to increase performance, towing capacity, and fuel economy by removing the systems that create parasitic engine load. Those benefits accrue to the truck owner. The costs, in the form of elevated emissions, fall on everyone else: the people who live near the roads, the farmworkers in fields adjacent to freight corridors, the kids whose schools sit near logistics hubs, the elderly residents whose cardiovascular systems cannot absorb additional diesel particulate exposure.

The communities that bear the highest diesel exposure burden are disproportionately low-income and disproportionately communities of color. This is a documented, well-researched pattern in environmental justice literature. The people who benefit from cheap, easy defeat devices are largely not the people who absorb the health consequences. That gap, between who profits and who pays the biological price, is the defining economic inequality at the center of every defeat device case. The EPA’s settlement does not address that gap at all.

Meanwhile, the $267,680.21 (less than the annual compensation of many mid-level corporate compliance officers) that Wehrli pays represents a business cost, not a deterrent. Any rational actor looking at this math, 1,447 violations, maximum exposure of over $8 million, actual settlement under $270,000, walks away understanding that the risk-reward calculation favors selling defeat devices. The fine is the cost of doing business. The communities downwind pay the rest.

What Now?

What You Can Do

Report defeat device sellers directly to the EPA. The agency’s tip line for CAA violations is available through EPA’s enforcement portal. If you know of a shop selling EGR deletes, DPF removals, or ECM tunes marketed for on-road diesel vehicles, that information can trigger an inspection. The system only works if people who live with the consequences use it.

Connect with your local environmental justice organization. Groups working on diesel corridor air quality, freight route exposure, and community health monitoring operate in most metro areas. Organizations like the Clean Air Task Force, Earthjustice, and local mutual aid networks focused on environmental health can connect you with advocacy campaigns pushing for stronger defeat device penalties, stricter enforcement, and community air monitoring programs. The settlement in this case changed nothing for the people already breathing the exhaust. Organizing changes the system that produced that settlement.

Demand criminal referrals, not just civil penalties. The EPA’s consent agreement explicitly states it does not prevent criminal prosecution. The DOJ has prosecuted defeat device cases criminally before. A $267,680.21 civil fine spread across four installments does not deter a company from running this operation again. Criminal accountability does. Push your congressional representatives to demand that EPA refer systematic defeat device operations to DOJ for criminal investigation, not just administrative settlement.