ANYONE who bought an Adblue Delete kit - which was advertised in Big Rigs - might want to uninstall the device.
Truck Industry Council chief technical officer Simon Humphries has confirmed its installation is illegal.
And so have NSW, Victorian and Queensland authorities.
"If it is fitted, it will disable part of the emission control system," Mr Humphries said.
And if that happened, the truck would not run legally under Australian Design Rules.
Since finding out the device is illegal, it is no longer being advertised in Big Rigs.
Mr Humphries said it was apparent at a recent seminar about Adblue that enforcement agencies "really don't know how to police it" - or what to look for.
"There is no way of telling from looking at a truck (if the device has been installed)," he said. But "a well educated enforcement officer would be able to slap a fine on the driver or owner".
Mr Humphries said Adblue was a urea solution required in SCR engines so levels of nitrogen oxide emissions were legal to Euro V standards and equivalent.
The solution is injected into the exhaust to convert the gas to nitrogen and water. So if you turn off Adblue, a truck will have higher-than-legal nitrogen oxide emissions.
Mr Humphries said he imagined the device would tell the engine computer that Adblue was not needed.
"It would save money," he said but the engine would no longer comply. And it might void a vehicle's warranty - "it might tamper with other electronics".
The devices were first drawn to the TIC's attention when it saw an advertisement. Now the TIC has written to Customs to see if it can stop their importation.
Mr Humphries said the TIC believed that putting them on the restricted list would help stop their use.
Since receiving the letter, Customs has passed on a request to the Department of Transport asking if there is a law that prohibits such a device.
A Customs and Border Protection spokesperson said the matter had been referred to the Department of Infrastructure and Transport for its consideration.
"The Australian Design Rules for emission control devices for heavy commercial vehicles are governed by Motor Vehicles Standards Act 1989, which is administered by the department," the spokesperson said.
"Customs and Border Protection will consult with Infrastructure and Transport.
"However, it should be noted that the World Trade Organisation's trading rules do not support the introduction of import bans unless equivalent domestic laws are in place," the spokesperson said.
Big Rigs has asked the department if there is such a law but we are still waiting for confirmation.
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