Well, if you come to think about it, you can make some connections.. if it's an air leak (lean mixture), than your idle should be going up and down. So if idle is all right, than you can think about something else. If it's your FPR, again, idle might be a bit lower than usually and exhaust tips will be black. If it's not the case, you can move on. These are just general examples, just to give an idea how you might use these codes for troubleshooting. Try to think of the more likely things to happen (like hose splits in these case or lambda itself), rather than things less likely to go wrong (like injectors, intake/exhaust valves etc).
And more specific on your problem: I had the exact same code when I first done the mod, but to me it was a lot easier. I already knew that my lambda sensor was shot so I just bought a new one and fit it. Problem solved. I think that might be your case as well, especially if your car has high-ish mileage and oxygen sensor has never been replaced.
Hope it helps and good luck with your diagnose!