If the CEL is on. I would first take the Rover to AutoZone to pull the codes (there will be no charge for this). Once you have them take them and plug them into this site: http://www.iequus.com/obd_def.asp
Sputtering could be: the fuel filter has gone bad, plugs or wires, misfire on a cylinder, fuel pump dying. Most of the aforementioned are fairly easy to change out if you have rudimentary mechanic skills and a manual. Good Luck. If it were me I would avoid the dealer like the plague!