Complex sentence: The X305 was equipped with an On-Board Diagnostics System, however, it failed to fully meet the OBD-II specifications, which became mandatory for the 1996 model year in the US.
Split into simpler sentences: The X305 was equipped with an On-Board Diagnostics System. However, it failed to fully meet the OBD-II specifications, which became mandatory for the 1996 model year in the US.