If it is an Orange Light with what looks like a white asterix inside it, then it is the "ENgine Management Light"
Is the veicle an automatic?
If it is then it is probably a sign of a fault developing with the automatic transmission.
As said previously, get it to a dealer (or ask around your friends and find out if anyone has a "Lexia Diagnostic kit"), get them to read the fault code and reset the light.
dependant on what the fault code is you will have to decide whether to spend money on getting the problem repaired or to take the cheaper way out and sell the car whilst the light is reset.
Being an honest person you will obviously do the right thing and notify the buyer of the vehicle about the fault.
Or maybe not.
Hope that helps
Stephen H
November 2011