management light on

kalos 2006 1.4 engine management light on had lots of replacement parts but light will not go off seems at times that it is running rough.replacement parts are battery, 2 x spark plugs,coil pack,crankshaft sensor,supposed to be a vauxhall engine,had car from new,been a problem now for 6 to 8 weeks,so far cost lots of money but still the problem exists