Division 2.5 F1
United Kingdom
Section 3.3.3.1 of Annex 11 to UNECE Regulation No 83 shall be understood as:
The OBD system shall monitor the reduction in the efficiency of the catalytic converter with respect to emissions of NMHC and NOx. Manufacturers may monitor the front catalyst alone or in combination with the next catalyst(s) downstream. Each monitored catalyst or catalyst combination shall be considered malfunctioning when the emissions exceed the NMHC or NOx threshold limits provided for in Section 2.3 of this Annex. By way of derogation, the requirement of monitoring the reduction in the efficiency of the catalytic converter with respect to NOx emissions shall only apply as from the dates set out in Article 17.