On-board diagnostics for control of vehicle emissions

Within the EC, new motor vehicles are subject to type approval and conformity of production requirements that seek to ensure that they meet tailpipe emission standards for carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen (NO/sub x/) and, in the case of diesels, particulates when they first enter into service. On-board diagnostics (OBD) is an area of automotive technology that is developing rapidly, not just for emissions. From the point of view of the authority, OBD offers the possibility of maintaining emissions performance over a vehicle's lifetime. Simplistically, an OBD regulation or directive need only state that if certain emission thresholds are exceeded, the OBD system should recognise it and indicate to the driver that a fault exists, leaving system design and functioning to the manufacturer. However, the need for harmonising standards across world markets is clear in order to avoid a proliferation of standards for OBD systems and so the UK is taking the lead in Europe by making a proposal for OBD systems based on the EPA requirements for 1994 model year passenger cars and light commercial vehicles.<>