Check engine light - code readers

[jmdlister]

So I finally got my cheap bluetooth code reader and an Android app...

The fault code is P2098 - which seems to be a generic code for "Post Catalyst Fuel Trim System Too Lean Bank 2", although I've also seen it identified as "Signal Delay Time for Oxygen Sensor Ageing, Bank 2 – Above Limit"

So - CATs? Sensors? Exhaust leak? I can't hear any obvious exhaust leaks.

I thought I might try swapping round the O2 sensors left to right bank, and see if the code changes.

Any thoughts?