The Driver and Vehicle Standards Agency (DVSA) has issued a warning to commercial fleets after roadside checks uncovered “very high” levels of use of emissions-cheating devices that disable AdBlue systems. 

A pilot scheme of emissions checks found drivers were routinely bypassing their AdBlue systems, which are designed to drastically cut pollution levels for harmful emissions such as nitrous oxide.

The DVSA is warning lorry fleets that any evidence of emissions cheating on a tested vehicle will prompt a full inspection of the rest of a company’s fleet.

Already, a number of inquiries are planned into fleets that have been investigated.

In one example, an investigation prompted by a roadside check on a single vehicle revealed the company’s entire lorry fleet had been tampered with.

So-called modular devices are widely available to buy, but fitting them is illegal. DVSA is warning companies not to fit them or remove them immediately if they have been installed.

The DVSA also said there were cases of Euro VI engine management systems being remapped to bypass the AdBlue system.

The DVSA’s Del Evans told delegates at a Freight Transport Association’s Transport Manager conference: “It is disappointing to find really high levels of non-compliance, particularly with fitting AdBlue modulator devices, thereby bypassing the system.

“This is fraud and if you have these devices on your vehicles, you need to take them off, because I am sure the Traffic Commissioner is going to take an extremely dim view of this. 

“This is a deliberate act and with all the focus on clean air legislation, it is a political hot potato and you don’t want to be caught up in it.”

He added that there may be financial reasons for vehicle operators to consider cheating. For example, if an emission control system was unreliable, it could cost £3,000 to fix, whereas a defeat device can be sourced for just £50.

But Evans cautioned: “This is the same as fitting a switch to bypass your tachograph. The first batch of operators will be facing a public inquiry soon.”