Mate has an 07 H6 spec b 6mt, that keeps bringing up code P0420, cat efficiency low. To try to choose between O2 sensor problem or cat problem, is there a way to read O2 sensor voltages via ODB2 ? Cant find any docs that indicate the V are available or not. One garage reckoned probably a bad tank of fuel, but it has come up 3 times lately. Current plan is to get at the connectors and clean them with Deoxit in case its that simple.
thanks
jp 08 gtb 6mt wagon