The U.S. Environmental Protection Agency (EPA) shocked the public in late September when it revealed that Volkswagen used "defeat device" software to cheat on emissions tests.

Now the company faces angry customers, lawsuits, and hundreds of thousands of diesel cars that must be modified to meet emissions standards.

VW's scheme to bypass emissions regulations was unprecedented for a carmaker, but the concept is not entirely unheard of.

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While still not legal, it's possible for individual owners to bypass the emissions controls on their own diesels.

A quick Google search--along with some poking around online retailers including Amazon and eBay--turned up aftermarket products specifically meant to render different emissions-control equipment inoperable.

The Volkswagen "defeat device" relied entirely on software to change an engine's operating characteristics during an emissions test, but many aftermarket options require hardware modifications as well.

EGR bypass kit for Volkswagen TDI models with BEW, BHW engines

EGR bypass kit for Volkswagen TDI models with BEW, BHW engines

An exhaust-gas recirculation (EGR) system bypass kit for older VW TDI models selling on eBay for $29.99 includes steel block-off plates to redirect exhaust flow.

EGR systems feed some exhaust back into the cylinders to be burned again. This lowers the temperatures inside cylinders, and helps prevent the formation of nitrogen oxides.

There were several similar systems available, though most were offered for for full-size diesel trucks.

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Installing these kits likely requires modification of the engine-control software as well, as the deactivation of emissions-control equipment may trigger dashboard warning lights.

There were also several online listings for "AdBlue emulators," although seemingly only for heavy-duty trucks and commercial vehicles.

AdBlue is the trade name for urea fluid used in Selective Catalytic Reduction (SCR) exhaust aftertreatment systems. The liquid is sprayed into the exhaust stream to transform nitrogen oxides into pure nitrogen and carbon dioxide.

AdBlue emulator

AdBlue emulator

Many of the affected VW diesel cars lack SCR systems, and some analysts have speculated that these vehicles can't be made legal without them.

However, legality apparently isn't a concern for owners who willingly modify their diesel vehicles.

Many diesel car and truck owners do so for increased performance. Perhaps some reserve their modified vehicles for track use, making the inability to register them for use on public roads a nonissue.

It's also become fashionable among a small subset of diesel-truck enthusiasts to remove particulate filters to allow them to "roll coal"--belching thick clouds of noxious exhaust smoke as a way of showing off.

But anyone who tampers with emissions-control equipment is also violating Federal law.

Under Section 203 (a) of the Clean Air Act, it is illegal to sell or install any component designed to "bypass, defeat, or render inoperative any device or element of design" installed to comply with air-quality standards.

Pickup truck

Pickup truck

Individuals who violate that provision face a civil penalty of up to $2,500.

In 2013, aftermarket electronics manufacturer Edge Products agreed to pay a $500,000 penalty for selling devices that allowed owners of diesel trucks built in 2007 or later to disable their emission controls.

Penalties against tampering with emissions controls ensures the anticipated benefits of cleaner vehicles will be realized--but that apparently doesn't mean people won't try to find a way around them.

[hat tip: Martin Smith]


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