The Department for Transport (DfT) is investigating the impact of AdBlue cheat devices amid calls from manufacturers and trade associations for them to be banned.

Fitting a selective catalytic reduction (SCR) bypass device, known as an emulator, to a truck enables operators to dupe the system’s control module and thus avoid the requirement for AdBlue.

However, vehicles fitted with emulators are likely to have higher exhaust emissions and thus not be compliant with Euro 4, 5 or 6 standards. Most trucks manufactured since Euro 4 emissions standards were introduced in October 2005 use an SCR system to control nitrogen oxide (NOx) emissions.

With improving air quality high on the Government’s agenda, there are fears that a failure to ban such modifications could result in overall emission levels not being met and, as a consequence, even tougher legislation being introduced that would affect all commercial vehicle operators.

A spokesman for one truck manufacturer, who wished to remain anonymous, told Commercial Fleet: “Our concern is not that major fleets will fit these devices, but as trucks that require AdBlue filter into the used market, small operators and owner/drivers may seek to fit the devices to save money. That is where the temptation will be greatest.”

The Society of Motor Manufacturers and Traders said it is working with the Government to try to find a solution.

An internet search revealed that SCR emulators were easy to obtain, with sellers suggesting that when AdBlue systems went wrong they could cost as much as £6,000 to fix. They also claimed that using AdBlue can increase vehicle fuel usage, so fitting an emulator would reduce diesel bills.

Sellers say the device overrides the SCR system and works without any interruption to operation of other truck systems so there will be no any engine power loss or black smoke and the vehicle’s gearbox will not jump to limp mode.

Nevertheless, they warn truck operators: “By buying this device you take full responsibility for the use of the device and the associated consequences. It’s your personal decision to use SCR emulator or not. We take no responsibility if this device is fitted contrary to any applicable legislation.”

Sellers add that the sale of emulators are “oriented to countries where there are no laws requiring Euro 4/5/6 ecological standards compliance”.

Ray Engley, head of technical services at the Road Haulage Association (RHA), said: “The Department for Transport is aware of these devices and is investigating. Tests are being undertaken as to the effectiveness of these devices and their impact on truck emissions and then the Department may  be prepared to act. We are awaiting the results of that  investigation.”

Commercial Fleet found emulators for sale online from £70+VAT, although they could be bought from Europe and the United States for less, with sellers claiming the ‘box’ could be fitted to a truck, bus or any other heavy vehicle in about an hour.

Andy Mair, head of engineering at the Freight Transport Association (FTA), said: “Post-type approval modifications to emissions control systems are likely to result in the harmful emissions of engines not being within the strict Euro levels, which they should be meeting.”

The introduction of Euro 6 regulations for trucks brings with it a requirement for in-service emissions testing for the first time. Mair predicted that would go some way to prevent the modification of vehicles with cheat devices. However, he said it may not eliminate the problem as it involved only sample testing of vehicles.

Although in-service emissions testing is detailed in the Euro 6 legislation, how it will be implemented nationally is still to be fully determined, not least with the recent EU referendum result.

Mair explained: “The legislation requires manufacturers to demonstrate that engines comply with emission limit values over an extended operating lifespan, dependent on vehicle category. This requirement, a part of type approval, must demonstrate verification of the correct operation of emission control devices during the life of the vehicle under normal conditions of use. In practice, vehicles are likely to be recalled from service to undergo in-service conformity testing.”