Emission light stays on zafira 2004 1.8?

The light with spanner came at first,then the tracking light came on.when the car is restarted the tracking light is off but spanner light remains on.After a few days the emission light and spanner came on.Now the emission light is the only one left on after a few miles.There is no drop in power or engine stalling.Can anyone advise please before being rip off by dealer.Thanks in advance.Amo de