When you get the GAP tool be sure to set it to show all codes. I can't remember which box isn't ticked that needs to be but if not ticked then it won't show some faults (pending?).
When a fault occurs, connect the tool and read the codes before switching off the engine in case it's a fault that clears on restart.
Even if the codes don't mean enough to you, there are lots of people on AULRO who can point you in the right direction.
