Division 2.3.2

For engines fuelled with compressed natural gas/biomethane (CNG) which are self-adaptive for the range of H-gases on the one hand and the range of L-gases on the other hand, and which switch between the H-range and the L-range by means of a switch, the parent engine shall be tested on the relevant reference fuel as specified in in Annex IX for each range, at each position of the switch. The fuels are G_R (fuel 1) and G₂₃ (fuel 3) for the H-range of gases and G₂₅ (fuel 2) and G₂₃ (fuel 3) for the L-range of gases, or the equivalent fuels created using admixtures of pipeline gas with other gases as specified in Appendix 1 of Annex IX. The parent engine shall meet the requirements of this Regulation at both positions of the switch without any readjustment to the fuelling between the two tests at each position of the switch. One adaptation run is permitted after the change of the fuel. The adaption run shall consist of performing the pre-conditioning for the following emission test according to the respective test cycle. In the case of engines tested on the NRSC, where the pre-conditioning cycle is inadequate for the engine fuelling to self-adapt an alternative adaption run specified by the manufacturer may be performed prior to pre-conditioning the engine.