ANNEX X U.K. ON-BOARD DIAGNOSTICS

6. IN USE PERFORMANCE REQUIREMENTS U.K.

6.1. Technical requirements U.K.

6.1.1. The technical requirements for assessing the in-use performance of OBD systems including requirements concerning communication protocols, numerators, denominators and their increment shall be those set out in Annex 9C to UN/ECE Regulation No 49. U.K.

6.1.2. In particular, the in-use performance ratio (IUPR_m) of a specific monitor m of the OBD system shall be calculated by the following formula: U.K.

IUPR_m = Numerator_m / Denominator_m

where:

• ‘Numerator_m’ means the numerator of a specific monitor m and is a counter indicating the number of times a vehicle has been operated in such a way that all monitoring conditions necessary for that specific monitor to detect a malfunction have been encountered; and

• ‘Denominator_m’ means the denominator of a specific monitor m and is a counter indicating the number of vehicle driving cycles that are of relevance to that specific monitor (or, ‘in which events occur that are of relevance to that specific monitor’).

6.1.3. The in-use performance ratio (IUPR_g) of a group g of monitors on board a vehicle is calculated by the following formula: U.K.

IUPR_g = Numerator_g / Denominator_g

where:

• ‘Numerator_g’ means the numerator of a group g of monitors and is the actual value (Numerator_m) of the specific monitor m that has the lowest in-use performance ratio as defined in Section 6.1.2 of all monitors within that group g of monitors on board a particular vehicle; and

• ‘Denominator_g’ means the denominator of a group g of monitors and is the actual value (Denominator_m) of the specific monitor m that has the lowest in-use performance ratio as defined in Section 6.1.2 of all monitors within that group g of monitors on board a particular vehicle.