Just bought a Lovely 2002 Omega , 2  owner , fsh , 34k , 2198 c.c. Auto , first week home ( after a fault-less 170 mile trip home ) A yellow fault light comes on after 15 or so miles , A car with a spanner going vertical thro'/ above car roof line - goes of with ignition ..... 15 miles later ... Back on , So , So , So mutch conflicting guff on Google ect.  I reckon the best people to ask are the true petrol head experts ...... & , PLEASE , Don't try tell me it's totally xxxx'd  & buy her for peanuts , Not every one wants a Hearse !  Thank you in advance . Skully. 

Lamp is showing an Engine Management fault lamp 

Best bet is to get a scanner to extract fault codes

To be fair, the Motronic Engine Management system used on the car is very simple and usually completely reliable