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This publication is available at https://www.gov.uk/government/publications/catalytic-convertors/catalytic-converters-advice-on-type-approval-and-legal-requirements-for-suppliers-and-manufacturers
What is a catalytic converter?
Catalytic converters are the most important parts of a car’s emission control system. These devices are fitted to a diesel or petrol vehicle to reduce the level of harmful pollutants exiting the tailpipe as exhaust gases. They achieve this by enabling chemical reactions to occur within the vehicle exhaust that convert harmful pollutants, such as nitrogen oxides, carbon monoxide and hydrocarbons, into less harmful products such as carbon dioxide and water. Many types of catalytic converter exist and modern vehicles will often possess multiple different devices to remove different components of the exhaust gas. In this way, these devices enable vehicles to meet European emission standards, improving air quality and reducing impacts on health.
Type approval of catalytic converters
Pollution control devices such as catalytic converters are required to pass strict emissions testing procedures as part of the type approval process before they can be sold in Europe. Testing typically involves the measurement of emissions at the vehicle tailpipe during a laboratory driving cycle, but also includes real-world emissions testing for new vehicles. These tests ensure that the relevant European emission standard is met, thereby reducing the vehicle’s impact on air quality and health.
Similar requirements apply to replacement catalytic converters, which should enable a vehicle to comply with the regulations to which it was originally approved. During approval a replacement catalytic converter is tested on a vehicle type that it is intended to be installed on. The tailpipe emissions are measured and are compared to that of an original catalytic converter. The replacement must also meet any relevant durability, noise and vehicle performance requirements in order to gain approval. If successful, an international approval mark will be added to the replacement catalytic converter to enable it to be sold.
Manufacturers, and suppliers and distributors of replacement catalytic converters have a legal duty to ensure the products they design, manufacture and sell comply with the applicable laws, including approval requirements governing the fitting to certain vehicles.
The approval requirements for replacement catalytic converters are set out in the Motor Vehicles (Replacement of Catalytic Converters and Pollution Control Devices) Regulations 2009.
Examples of non-compliant behaviour would include:
- the sale of non-approved catalytic converters for vehicles that require only approved units
- the sale of non-approved replacement diesel particulate filters (DPFs) for Euro 5 (and onwards) vehicles (a separate information sheet is provided on this subject)
- the supply and fitment of approved catalytic converters and DPFs for and to vehicles that are not covered by the scope of the approval and not listed on the relevant approval documentation, eg a catalytic converter is approved to only fit manufacturer A’s vehicles, but is sold for fitment to manufacturer B’s vehicle
We are committed to enforcing vehicle safety and environmental standards. The Department for Transport’s Market Surveillance Unit (MSU) will continue to check that vehicles and components available on the UK market comply with the legislative requirements to which they were approved. Manufacturers, suppliers and distributors who are found to have breached these requirements should expect to be the subject of enforcement action.
In addition to planned testing, the MSU will investigate areas of potential non-compliance that are brought to its attention. We welcome any information or concerns from within the relevant industries or from members of the public. If you would like to contact the MSU then please email: email@example.com. The information that you supply will be considered carefully by the MSU who will decide whether further investigation is needed.
Breaching the requirements of the 2009 Regulations can amount to a criminal offence, punishable by a fine of up to £5,000.
It is also an offence under the Road Vehicles (Construction and Use) Regulations (Regulation 61a(3)) to use a vehicle which has been modified in such a way that it no longer complies with the air pollutant emissions standards it was designed to meet. The potential penalties for failing to comply with Regulation 61a are fines of up to £1,000 for a car or £2,500 for a light goods vehicle.
Useful sources of legislation
- Replacement Catalytic Converter Regulations
- Road Vehicles (Construction and Use) Regulations (in un-amended form)
- European Regulations 715/2007, 692/2008 and 2017/1151
- UNECE Regulation 103
The information in this document is a summary of the department’s understanding of what the law requires. However, ultimately the interpretation of the law is a matter for the courts based on individual facts of any particular case. You are therefore advised to consult the relevant legislation and, if necessary, seek independent advice.