i got a £20 ELM reader off e-bay and used ODBII diag software for my laptop, I think, but i also have a hand held one which I keep in the car for emergencies (which thankfully have not happened in a while!) they all give you codes and generally will clear them too. you wont get a listing telling you what the Maserati special codes are , or indeed any of the funky setup functions the garage has access to with the SD2 and SD£ testers, but its useful just the same. I also keep a note pad in the car and any error codes are logged and dated before clearing, this is important or you loose the info on what is going on.