I'm wondering how specific the diagnostics are via the OBC port when trying to diagnose a fault?
Specifically I had a starting problem recently which the garage had a look at. They came back and said the diagnostics showed it was the fuel pump (in the fuel tank) which was faulty hence they replaced it. Since getting the car back the problem is still there so I'm concerned they replaced a part that didn't need replacing.
Do the diagnostics often point to a specific part or do they just generalise a problem as 'fuel problem' say?