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For as long as there have been emissions regulations, there have been tuners disabling them in pursuit of more speed and more power. But the industry has always been hush-hush. Then in September 2023, the DOJ threatened eBay with $1.9 billion in fines for hosting the sale of flagrantly advertised diesel truck emissions defeat devices. To be blunt, some deleted diesel truck drivers have gleefully thumbed their nose at the government for years. The DOJ fine is the latest form of legal blowback they have invited. This reaction to the diesel tuners will make it harder for anyone to tune any engine going forward.

The long silent history of emissions defeat devices

Tailpipe of a diesel Volkswagen failing emissions guidelines because of a defeat device.
2012 VW Golf 2.0 TDI testing | Patrick Pleul/picture alliance via Getty Images

As long as there have been emissions regulations, both automakers and tuners have found workarounds. This is because limiting emissions often requires limiting an engine’s power and sometimes its fuel efficiency.

Way back in 1973, the EPA ordered Detroit to stop using ambient temperature switches to affect how their engines run. The agency called these switches a “defeat device” because they defeated the testing process. All of the automakers stopped using them but maintained the switches were simply engineered to make engines more efficient. Volkswagen even had to pay a fine, but again, admitted no wrongdoing.

Through the 1990s and 2000s, the EPA caught the automakers building more flagrant defeat devices into their vehicles. These included ECUs that assumed if the heat or A/C weren’t running, the vehicle might be in the middle of an emissions dyno test and should run cleaner (Cadillac). An ECU that assumed if the door was open at high speeds, it was on a dyno (Mercedes). Or even an ECU that assumed if the car ran in a straight line for long enough, it was on a Dyno (Volkswagen, again).

As the EPA cracked down on the automakers, the aftermarket crowd found ingenious workarounds. Many modifications for “tuning” a car for extra power increase emissions. For this reason, many modifiers or aftermarket suppliers labeled their services “for track use only” or “for off-road use only.” But not deleted diesel truck tuners.

The rise of ‘deleted’ diesel trucks

Deleted diesel pickup truck rolling coal on Pismo Beach in California.
Diesel Chevrolet Silverado heavy-duty | George Rose via Getty Images

Beginning in 2003, the EPA rolled out strict regulations limiting the amount of NOx gas a diesel engine could emit. NOx is not a greenhouse gas (so it does not contribute to global warming), but it contributes greatly to smog and may pose health risks.

The best way to reduce NOx emissions is to reduce the temperature of the combustion cycle. Adjusting an engine to reduce NOx emissions requires sacrificing both power and MPG. This is why 1980s and 1990s diesel trucks often get higher MPG than their mid-2000s counterparts.

Many truck buyers, used to the older engines, bought new diesels and “deleted” these emissions controls. This usually required an aftermarket ECU chip. On some engines, they physically deleted the EGR system or other components. Buying a “deleted” truck often promised more power and better MPG than you could expect stock.

But unlike the tuners of past generations, many diesel truck owners bragged that their rigs were “deleted.” Online stores, even hosted on sites such as eBay, listed the everyday benefits of installing their illegal delete devices for road use. And folks advertising their used diesel trucks detailed how these vehicles had been deleted, hoping to command a higher sales price.

Unlike previous generations of tuners, the latest generation of diesel truck modifiers created a culture of flagrant disregard for the law. And the consequences of this outlaw diesel movement are affecting all car enthusiasts.

The EPA strikes back

The offices of the Department of Justice in Washington DC, before it sued eBay over selling deleted diesel pickup truck devices.
Department of Justice | Drew Angerer via Getty Images

Some of the first retaliations to flagrant deleted diesel trucks came at the state level. The New Jersey Department of Environmental Protection put together a task force that messaged Facebook sellers bluntly advertising a deleted diesel on the marketplace. The DEP asked for details to confirm each truck was illegal, then mailed the owners a fix-it ticket.

Diesel truck tuners rejoiced when the EPA announced its priorities through 2027, and policing aftermarket delete devices didn’t make the list. But it turns out that even though the EPA now has a long list of higher priorities, it is far from ending its aftermarket emissions enforcement efforts.

In September 2023, the Department of Justice sued eBay over selling emissions defeat devices. Reuters reported the DOJ threatened a $1.9 billion in fines. The number certainly got eBay’s attention. The website promised it is “blocking and removing more than 99.9% of the listings for the products cited by the DOJ, including millions of listings each year.”

Going forward, you can bet eBay and its competitors will all be much more careful about the aftermarket automotive components they allow. This will include diesel defeat devices, which pollute a lot. But it will also include any modifications for gasoline or diesel engines that might pollute even a little. We are witnessing the end of being able to buy car parts on eBay “for track use only.” All thanks to outlaw diesel culture.

Why did deleted diesel outlaw culture ruin it for the rest of us?

A white heavy-duty Ram truck with a Cummins engine parked in the woods.
Cummins-powered heavy-duty Ram | Caelen Cockrum via Unsplash

How did this outlaw culture come about? First, we can all agree that it must have been frustrating for truck buyers to spend their hard-earned money on a brand-new diesel only to get less power and MPG than their old truck. Such a bait-and-switch could push law-abiding citizens to break the law. The rest of us stigmatizing diesels–even emissions-compliant trucks–is another effective way to make law-abiding citizens feel like outsiders.

Do note that this is as much the automakers’ fault as the government’s. Automakers spent millions lobbying against the laws and waited until the last possible moment before throwing together engines to meet the 2003 regulations. The result was engines such as Ford’s notoriously unreliable Power Stroke 6.0. Today, automakers have found a better balance of reduced NOx and performance. But not after they pawned a generation of lame diesels off on consumers.

There is another element of outlaw diesel culture. Most diesel pickup truck drivers I know are good, hardworking folks. But I’ve encountered others who drive a deleted diesel as a form of rebellion. These are the ones who roll coal the moment they see a Prius. Deleted diesels are their identity. The problem with an outlaw culture is that while it stands against the status quo, it doesn’t necessarily stand for anything. Ideally, the vehicle you drive should reflect who you are at your core. But it can’t make up for a lack of real identity.

Whatever caused the outlaw diesel culture, it contributed to government blowback that will affect every automotive enthusiast from now until forever. Would we have faced a crackdown on buying tuner parts online without outlaw diesel culture? Let us know what you think in the comments below.

Next, read about a smart alternative to the looming combustion ban, or learn more about the eBay lawsuit in the video below: