Last reviewed 25 June 2018

AdBlue is a chemical which reduces nitrogen oxide (NOx) emissions from diesel engines. Its use is essential for many vehicles to meet Euro 4 or better emissions standards. Following a crackdown by the Driver and Vehicle Standards Agency (DVSA), Traffic Commissioners have been taking a strong line where operators have been fitting devices to avoid the use of AdBlue, including the revocation of licences and the disqualification of operators and transport managers. Michael Jewell reports on two recent cases and the view taken by the Traffic Commissioners.


Vehicle manufacturers have sought to reduce carbon dioxide emissions through the development of vehicles with a lean-burn air-to-fuel ratio to ensure full combustion of all fuel and to eradicate the emission of unburnt hydrocarbons. The excess air however produces NOx.

Poor air quality is argued to be the largest environmental risk to public health in the UK. One approach to reducing NOx in the atmosphere has been to treat vehicle exhaust gases to remove NOx. This is achieved by injecting a diesel exhaust fluid comprising urea and deionised water to those exhaust gases. This fluid is known as AdBlue.

Vehicles requiring treatment of emissions through the use of AdBlue fall into one or other of a series of categories of Euro-rated vehicle, which have developed increasingly cleaner operation.

A Euro IV vehicle requirement brought down acceptable level of NOx emissions from 5g/kWh to 3.5g/kWh. Euro V reduced this to 2g/kWh, and Euro VI to 0.4g/kWh.

Essentially, in order to comply with EU emissions standards, the AdBlue is added at the rate of 4–7% of diesel used through a separate small tank. The fluid combines with the gas to convert NOx, into harmless nitrogen and water.


The devices found have the effect of turning off the use of AdBlue and disabling the warning light on the dashboard which would have warned the driver that the AdBlue system was not functioning. Estimates suggest that the impact of fitting an AdBlue emulation or cheat device to a vehicle requiring AdBlue is to increase harmful emissions into the atmosphere by one-third at least, but at worst by up to 21/2 times. This is because it effectively returns the vehicle to the Euro III standard, so it will have increased from either 2g/kWh or 3.5g/kWh, up to 5g/kWh.

Deliberately interfering with a vehicle’s NOx management systems so as to make a vehicle non-compliant with the applicable emissions limits is undermining the whole purpose of vehicle emissions legislation determined by the EU Council of Ministers. This is progressive over time, intended to reduce NOx emissions from the EU’s vehicle fleet and therefore to reduce NOx levels in the air.

For operators, if something goes wrong with the AdBlue system, it can be an expensive process to rectify. In a number of cases, hauliers have bought vehicles without being aware that cheat devices have been fitted. Many operators considered there was not a problem with the use of such devices if they were not going in the London Low Emission Zone.

The view of the Traffic Commissioners

The general view expressed by the Commissioners is that the fitting of an emulator is equivalent, for example, to using a magnet to interrupt a tachograph. Each is an act of fraud and each can kill: one just does it more violently and quickly than the other.

The effect on fair competition is not just reflected in the financial savings in purchasing AdBlue. It is also reflected in the savings in maintaining a properly functioning vehicle emissions warning system and remedying any faults in levels of pollutants being emitted. It can also reduce downtime for the operator where modern emission management systems can put the engine into “limp mode” or prevent the engine from starting if the emissions control systems are not maintained or working correctly.

The issue has been extensively covered and discussed in the trade, the national press, on the internet and on national television over a number of years. The availability of such devices cannot have escaped the attention of anyone connected with the haulage industry. This is particularly the case for operators, transport managers and professional drivers.

In order to illustrate the view being taken by the Traffic Commissioners, a number of the cases to come before them are highlighted.

In a case which is now under appeal, Traffic Commissioner Kevin Rooney revoked the licence for 40 vehicles and 80 trailers held by Southampton based IPL Haulage Ltd and disqualified Director Ian Percival for two years from acting as a Transport Manager. The company was called to public inquiry after a vehicle was issued with an “S” marked prohibition after it was found to be fitted with an emission cheat device.

Mr Percival conceded that the device was fitted to mask an AdBlue system defect to enable the vehicle to pass its MOT in October 2017. Mr Percival took the decision based on a commercial need to get the vehicle back on the road to fulfil a contract. At the time, IPL Haulage was waiting for delivery of replacement vehicles which were due in September 2017 but arrived October 2017.

In his decision, the Commissioner said that Mr Percival had allowed commercial considerations to lead him to undertake fraudulent acts. The fitment of the AdBlue cheat device was a deliberate and reckless act that led to a commercial advantage and put public health at risk.

In another case, also under appeal, the use of devices disabling the use of AdBlue in a number of its vehicles has led to the revocation of the licence for 35 vehicles and 34 trailers held by Cockermouth based EW & PA Nicholson, trading as Nicholson Transport, and the company’s disqualification from holding or obtaining an O-licence for five years. In addition, Traffic Commissioner Simon Evans disqualified former Director Eric Nicholson from acting as a Transport Manager indefinitely.

Eric Nicholson said that when the Euro 5 DAFs got to a certain age, they could not stop the AdBlue light coming on. There was an ongoing wiring problem which they were unable to sort out. He paid someone cash to fit the emulators. About 10 or 11 of the vehicles were fitted with emulators.

In making the revocation and disqualification orders, the Commissioner said that fitting emulators is a matter of trust; the words cheat and fiddle come to mind. He took a most serious view of Mr Nicholson’s conduct, which would have led to the company gaining a significant unfair competitive advantage. He could not but characterise the use of an emulator device to be anything other than akin to the use of a magnet deployed to interrupt accurate tachograph recording. Each was an act of deceit, unbecoming of a licence holder. The safety of the public as a whole was threatened by acts such as that.

In a further case, Deputy Traffic Commissioner Anthony Secular cut the licence of Gwynedd Environmental Waste Services Ltd from 25 vehicles to 15 for a period of three months and disqualified Director Dafydd Price Thomas from acting as a Transport Manager indefinitely after 20 of the company’s vehicles were found to be fitted with emulator devices.

The company’s explanation was that the emulators were fitted to overcome technical difficulties with the emissions warning systems in some vehicles.

In his decision, the Deputy Commissioner said that the use of cheating devices which; compromise public health, give the operator a commercial advantage over other operators maintaining correctly functioning emissions warning systems, and, requires drivers to collude in operating compromised systems, must come into the “ambit of severe” regulatory action.

In deciding what action to take, he took account of the management changes since made by the company.


The use of such devices clearly puts the repute and livelihood of operators and qualified transport managers at risk: the Commissioners are taking action designed to send a clear message to them that the fitting of AdBlue cheat devices is illegal and will lead to serious consequences.