Diesel Vehicles: Defeat Devices

Simon Lightwood Excerpts

Wednesday 25th February 2026 Westminster Hall

[The Parliamentary Under-Secretary of State for Transport (Simon Lightwood)]

It is a pleasure to see you, Ms Lewell—my favourite sand dancer—chairing the debate this morning. I congratulate my hon. Friend the Member for Ealing Central and Acton (Dr Huq) on securing this debate on defeat devices in diesel vehicles. This is an important subject that rightly attracts scrutiny from Parliament, the public and campaigners. I acknowledge the concerns that my hon. Friend set out in her parliamentary questions and recent public commentary, which reflect the strength of feeling about this issue and the need for transparency and accountability from both manufacturers and regulators. Those concerns are entirely legitimate, and I welcome the opportunity to set out clearly how they align with the Government’s determination to uphold emissions standards and to ensure that the public can have full confidence in the environmental performance of vehicles on our roads.

I begin by reaffirming this Government’s commitment to delivering greener, cleaner transport and to reducing harmful emissions that affect communities across the country. Road transport emissions have significant implications for public health. We continue to take firm, evidence-based action wherever practices risk undermining public trust or air quality. Alongside our compliance and enforcement work, we are delivering wider measures to cut harmful emissions, including by supporting the transition to zero-emission vehicles, as my hon. Friend referenced.

We have consistently said that prohibited defeat devices are illegal, are misleading for drivers and can have negative impacts on the public. My Department has considerably strengthened its oversight of vehicle emissions in recent years. Since 2016, the Driver and Vehicle Standards Agency’s vehicle market surveillance unit has carried out increasingly rigorous emissions testing programmes using both laboratory and real-world methods to identify suspicious performance. The DVSA actively investigates potential non-compliance, and where its assessments identify issues, manufacturers are required to take corrective action in line with DVSA’s published enforcement policy.

This Government are undertaking a targeted and comprehensive programme of assessments, which formally commenced in early 2025, to assess a range of Euro 5 and Euro 6 diesel cars and vans produced between 2010 and 2018. As my hon. Friend would probably expect, we are focusing on vehicles with the greatest potential to cause harm, and our remediation actions are designed to reduce real-world emissions as quickly and effectively as possible. Although those models are no longer entering the market, they remain on our roads and the public quite rightly expect them to meet the standards set out at approval. I think, at present, there are 110 individual vehicle models that are under active investigation. That reflects the scale and complexity of the challenge.

To be absolutely clear, every vehicle model within scope will undergo a full assessment, and manufacturers are now working to firm, defined deadlines. The DVSA has completed assessments on a number of models and is now reviewing detailed submissions from manufacturers, with further assessments underway. We will conclude the process as soon as evidence allows, to ensure that any findings are robust, fair and accountable. Where non-compliance is identified, manufacturers will be required to take corrective action and enforcement will escalate where deadlines are not met. That approach is intended to achieve real-world improvements in air quality swiftly and fairly.

The Government have also strengthened the enforcement framework available to regulators. Since 2018, it has been an offence to place vehicles containing prohibited defeat systems on the market. My Department is equipped to require swift corrective action to address non-compliance. We are also considering whether we need to go further and build on our existing powers under assimilated EU law to require compulsory environmental recalls to deliver the intended outcomes.

Let me be clear: if non-compliance is confirmed, the DVSA will require manufacturers to take whatever remedial action is necessary, at no cost to consumers. Where any serious risk is evidenced, that remedial action must be taken without delay.

On transparency, I fully recognise the public interest in understanding the outcomes of this work, and manufacturer-specific findings will be published once investigations are complete and decisions are final. That approach is entirely consistent with other market surveillance activity. Waiting until that point is important to ensure that due process is followed, to avoid prejudicing live investigations and to maintain the integrity of any future enforcement action.

[Dr Huq]

I like what I have heard so far because, up to now, this has all been a bit mysterious. I wonder if it might be a good idea for me to meet the Minister. As a London MP, I have experience with ULEZ—we have a riding school in my seat, and an exemption was made for a horsebox. As I have experience of what happens in London, it would be good to talk this through, but it is impossible in a debate like this. Would the Minister meet me at some point?

[Simon Lightwood]

How could I refuse? Of course I will meet my hon. Friend.

Publishing incomplete or provisional findings would risk misleading consumers and compromising the quality of the technical assessments underway, as my hon. Friend will appreciate. To support transparency, I am pleased to say that the Department will shortly publish its dedicated gov.uk landing page. That will bring together all the emissions compliance publications, and once investigations are concluded, the final outcomes of the programme will be added to that page for full public access.

The programme has been developed in close collaboration with the Department for Business and Trade, the Department for Environment, Food and Rural Affairs and the UK Health Security Agency. That ensures that our approach draws on the full breadth of Government expertise. That collective effort means that our response is co-ordinated and informed by those who play a direct role in delivering cleaner, safer vehicles.

We are closely following the Pan-NOx group litigation concerning alleged defeat devices. Once the court hands down its judgment, we will consider carefully any implications, including whether changes are needed to our policy framework or enforcement approach. Internationally, we continue to work closely with regulators in EU member states, which helps us to anticipate emerging issues, align on best practice and ensure that manufacturers face a coherent regulatory environment across markets. It reinforces our ability to act decisively where cross-border issues arise, recognising that emissions compliance is a global challenge.

To conclude, a great deal has been achieved, and more is underway. The Government are delivering a thorough and proportionate programme designed to address potential non-compliance swiftly, transparently and in line with our legal duties. Our shared objective is clear: deliver cleaner air, protect public health, uphold public confidence and ensure that the vehicles on our roads meet the standards that the public expect and deserve.

Question put and agreed to.