Instead of retrofitting an on-board ccmputer ….Turbo Gauge IV for OBDII including 4in1 scan car computer?

Hello Volvo specialists, my V40 Bj98 has unfortunately no BC and no temperature indicator. After reading many articles concerning the on-board computer I prefer to leave it with the retrofitting because I do not know if the connections are available and whether the control unit has to be unlocked. It is also mainly about the consumption indicator and of course further data would be practical and interesting. Now I am on this offer: Turbo Gauge IV for OBDII incl. 4in1 Scan Auto Computerhttp://cgi.ebay.de/ws/…rack=true&ssPageName=VIP:watchlink:top:de Maybe someone has experience with it or is the thing nix? Thank you and best regards Norbert