The US government has begun legal proceedings to halt sales of a device allegedly designed to defeat vehicle emissions systems.
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Companies offering products that enable diesel pick-ups to bypass emissions software – a phenomenon known as "rolling coal" due to the huge clouds of black smoke it creates – have come under scrutiny from the US government.

Earlier this week, the government filed a US federal court complaint against American company EZ Lynk for selling an aftermarket emissions defeat device advertised as a diagnostics and data-logging tool, news outlet Reuters reports.

The software allegedly permits owners of Chevrolet, GMC, Ford, and Ram pick-ups to change computer parameters which would normally disable the car when components such as the diesel particulate filter and exhaust gas recirculation system have been removed.

The product also lets owners upload their own engine 'tune', which changes the air/fuel ratio and boost settings for the turbo set by the factory.

Turbo-diesel engines in particular are known to see power increases of up to 20 per cent by adding fuel into the combustion cycle, in some cases creating smoke plumes known as "rolling coal".

"Emissions controls on cars and trucks protect the public from harmful effects of air pollution," a US government spokesperson said in a statement.

"EZ Lynk has put the public’s health at risk by manufacturing and selling devices intended to disable those emissions controls."