Hi Rayman,
It is unlikely that having your car serviced will put the engine management light out, although all cars should be serviced regularly, not having the car serviced would not in itself put the light on. it is most likely that one of the sensors that feed into the e.c.u has triggered the light, this could be any one of many things and you would need your car plugging into a diagnostics machine to read the e.c.u fault code and after repair put the light out by cancelling the codes from the e.c.u's memory there are many good garages out there offering this service but unfortunately it costs.
regards.
slurp