Vehicle exhaust emission standards

The procedure testers will follow to check vehicle exhaust emissions during the MOT test, and vehicle examiners follow to check emissions at the roadside.


In-service exhaust emission standards for road vehicles: 19th edition

This file may not be suitable for users of assistive technology. Request an accessible format.

If you use assistive technology (such as a screen reader) and need a version of this document in a more accessible format, please email Please tell us what format you need. It will help us if you say what assistive technology you use.


This booklet explains the vehicle exhaust emissions check procedures testers and vehicle examiners use during MOT tests and roadside checks.

It also contains emissions limits for vehicles fitted with advanced emissions control systems, such as 3-way catalytic converters, and offers general advice to motorists and vehicle operators on submitting vehicles for test.

The booklet deals with petrol and diesel vehicles separately.

Published 20 August 2014
Last updated 1 February 2018 + show all updates
  1. 19th edition of 'In service exhaust emission standards for road vehicles' including updated emissions data.
  2. First published.